feat(web): add SEO optimization — JSON-LD, dynamic sitemap, meta tags for listings

Add comprehensive SEO support for property listing pages to improve
organic search visibility and social sharing.

Changes:
- Convert listing detail page from client-only to server component wrapper
  with generateMetadata() for per-listing title, description, OG tags,
  canonical URLs, and hreflang alternates
- Add JSON-LD structured data (Schema.org RealEstateListing) with price,
  location, property specs, and breadcrumb markup
- Add Website JSON-LD with SearchAction to root layout
- Upgrade sitemap.xml to dynamically include all active listings across
  both locales (vi, en) with ISR revalidation
- Improve robots.txt with pagination/sort exclusions and GPTBot block
- Create server-side fetch utility (listings-server.ts) for SSR data
- Extract client UI into ListingDetailClient component

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/web/components/listings/listing-detail-client.tsx

@@ -0,0 +1,306 @@
+'use client';
+
+import dynamic from 'next/dynamic';
+import Link from 'next/link';
+import * as React from 'react';
+import { ImageGallery } from '@/components/listings/image-gallery';
+import { Badge } from '@/components/ui/badge';
+import { Button } from '@/components/ui/button';
+import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
+import { AiEstimateButton } from '@/components/valuation/ai-estimate-button';
+import type { ListingDetail } from '@/lib/listings-api';
+import { PROPERTY_TYPES, DIRECTIONS, TRANSACTION_TYPES } from '@/lib/validations/listings';
+
+const ListingMap = dynamic(
+  () => import('@/components/map/listing-map').then((mod) => mod.ListingMap),
+  {
+    ssr: false,
+    loading: () => (
+      <div className="flex h-[300px] items-center justify-center rounded-lg bg-muted">
+        <p className="text-sm text-muted-foreground">{'\u0110ang t\u1ea3i b\u1ea3n \u0111\u1ed3...'}</p>
+      </div>
+    ),
+  },
+);
+
+function formatPrice(priceVND: string): string {
+  const num = Number(priceVND);
+  if (num >= 1_000_000_000) return `${(num / 1_000_000_000).toFixed(1)} t\u1ef7`;
+  if (num >= 1_000_000) return `${(num / 1_000_000).toFixed(0)} tri\u1ec7u`;
+  return num.toLocaleString('vi-VN');
+}
+
+function getLabel(list: readonly { value: string; label: string }[], value: string | null) {
+  if (!value) return null;
+  return list.find((item) => item.value === value)?.label ?? value;
+}
+
+interface ListingDetailClientProps {
+  listing: ListingDetail;
+}
+
+export function ListingDetailClient({ listing }: ListingDetailClientProps) {
+  const { property, seller, agent } = listing;
+  const transactionLabel = getLabel(TRANSACTION_TYPES, listing.transactionType);
+  const propertyTypeLabel = getLabel(PROPERTY_TYPES, property.propertyType);
+
+  return (
+    <div className="mx-auto max-w-6xl px-4 py-6">
+      {/* Breadcrumb */}
+      <nav className="mb-4 flex items-center gap-1.5 text-sm text-muted-foreground">
+        <Link href="/" className="hover:text-foreground">Trang ch\u1ee7</Link>
+        <span>/</span>
+        <Link href="/search" className="hover:text-foreground">T\u00ecm ki\u1ebfm</Link>
+        <span>/</span>
+        <span className="truncate text-foreground">{property.title}</span>
+      </nav>
+
+      {/* Header */}
+      <div className="mb-6 flex flex-col gap-4 sm:flex-row sm:items-start sm:justify-between">
+        <div className="min-w-0 flex-1">
+          <div className="mb-2 flex flex-wrap items-center gap-2">
+            {transactionLabel && (
+              <Badge variant={listing.transactionType === 'SALE' ? 'default' : 'secondary'}>
+                {transactionLabel}
+              </Badge>
+            )}
+            {propertyTypeLabel && <Badge variant="outline">{propertyTypeLabel}</Badge>}
+          </div>
+          <h1 className="text-2xl font-bold md:text-3xl">{property.title}</h1>
+          <p className="mt-1 flex items-center gap-1 text-muted-foreground">
+            <svg className="h-4 w-4 shrink-0" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M17.657 16.657L13.414 20.9a1.998 1.998 0 01-2.827 0l-4.244-4.243a8 8 0 1111.314 0z" />
+              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M15 11a3 3 0 11-6 0 3 3 0 016 0z" />
+            </svg>
+            {property.address}, {property.ward}, {property.district}, {property.city}
+          </p>
+        </div>
+        <div className="shrink-0 text-right">
+          <p className="text-2xl font-bold text-primary md:text-3xl">{formatPrice(listing.priceVND)} VND</p>
+          {listing.pricePerM2 != null && (
+            <p className="text-sm text-muted-foreground">
+              ~{listing.pricePerM2.toLocaleString('vi-VN')} VND/m²
+            </p>
+          )}
+          {listing.rentPriceMonthly && (
+            <p className="text-sm text-muted-foreground">
+              Thu\u00ea: {formatPrice(listing.rentPriceMonthly)}/th\u00e1ng
+            </p>
+          )}
+        </div>
+      </div>
+
+      {/* Image gallery */}
+      <ImageGallery media={property.media} />
+
+      {/* Quick specs bar */}
+      <div className="my-6 flex flex-wrap gap-4 rounded-lg border bg-card p-4">
+        <QuickStat icon="area" label="Di\u1ec7n t\u00edch" value={`${property.areaM2} m\u00B2`} />
+        {property.bedrooms != null && (
+          <QuickStat icon="bed" label="Ph\u00f2ng ng\u1ee7" value={`${property.bedrooms}`} />
+        )}
+        {property.bathrooms != null && (
+          <QuickStat icon="bath" label="Phòng tắm" value={`${property.bathrooms}`} />
+        )}
+        {property.floors != null && (
+          <QuickStat icon="floors" label="Số tầng" value={`${property.floors}`} />
+        )}
+        {property.direction && (
+          <QuickStat icon="compass" label="Hướng" value={getLabel(DIRECTIONS, property.direction) || ''} />
+        )}
+      </div>
+
+      <div className="grid gap-6 lg:grid-cols-3">
+        {/* Main content */}
+        <div className="space-y-6 lg:col-span-2">
+          {/* Description */}
+          <Card>
+            <CardHeader>
+              <CardTitle>Mô tả</CardTitle>
+            </CardHeader>
+            <CardContent>
+              <p className="whitespace-pre-wrap text-sm leading-relaxed">{property.description}</p>
+            </CardContent>
+          </Card>
+
+          {/* Details */}
+          <Card>
+            <CardHeader>
+              <CardTitle>Thông tin chi tiết</CardTitle>
+            </CardHeader>
+            <CardContent>
+              <div className="grid grid-cols-2 gap-4 sm:grid-cols-3">
+                <InfoItem label="Loại BĐS" value={propertyTypeLabel || '---'} />
+                <InfoItem label="Diện tích" value={`${property.areaM2} m\u00B2`} />
+                <InfoItem label="Phòng ngủ" value={property.bedrooms != null ? `${property.bedrooms}` : '---'} />
+                <InfoItem label="Phòng tắm" value={property.bathrooms != null ? `${property.bathrooms}` : '---'} />
+                <InfoItem label="Số tầng" value={property.floors != null ? `${property.floors}` : '---'} />
+                <InfoItem label="Hướng" value={getLabel(DIRECTIONS, property.direction) || '---'} />
+                <InfoItem label="Năm xây" value={property.yearBuilt ? `${property.yearBuilt}` : '---'} />
+                <InfoItem label="Pháp lý" value={property.legalStatus || '---'} />
+                <InfoItem label="Dự án" value={property.projectName || '---'} />
+              </div>
+            </CardContent>
+          </Card>
+
+          {/* Amenities */}
+          {property.amenities && property.amenities.length > 0 && (
+            <Card>
+              <CardHeader>
+                <CardTitle>Tiện ích</CardTitle>
+              </CardHeader>
+              <CardContent>
+                <div className="flex flex-wrap gap-2">
+                  {property.amenities.map((a) => (
+                    <Badge key={a} variant="secondary">
+                      {a}
+                    </Badge>
+                  ))}
+                </div>
+              </CardContent>
+            </Card>
+          )}
+
+          {/* Map */}
+          <Card>
+            <CardHeader>
+              <CardTitle>Vị trí trên bản đồ</CardTitle>
+            </CardHeader>
+            <CardContent>
+              <ListingMap
+                listings={[listing]}
+                className="h-[300px]"
+              />
+            </CardContent>
+          </Card>
+        </div>
+
+        {/* Sidebar */}
+        <div className="space-y-6">
+          {/* Contact card */}
+          <Card className="lg:sticky lg:top-20">
+            <CardHeader>
+              <CardTitle>Liên hệ</CardTitle>
+            </CardHeader>
+            <CardContent className="space-y-4">
+              <div className="flex items-center gap-3">
+                <div className="flex h-10 w-10 items-center justify-center rounded-full bg-primary/10 text-primary">
+                  <svg className="h-5 w-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M16 7a4 4 0 11-8 0 4 4 0 018 0zM12 14a7 7 0 00-7 7h14a7 7 0 00-7-7z" />
+                  </svg>
+                </div>
+                <div>
+                  <p className="font-medium">{seller.fullName}</p>
+                  <p className="text-sm text-muted-foreground">{seller.phone}</p>
+                </div>
+              </div>
+
+              <a href={`tel:${seller.phone}`}>
+                <Button className="w-full gap-2">
+                  <svg className="h-4 w-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                    <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M3 5a2 2 0 012-2h3.28a1 1 0 01.948.684l1.498 4.493a1 1 0 01-.502 1.21l-2.257 1.13a11.042 11.042 0 005.516 5.516l1.13-2.257a1 1 0 011.21-.502l4.493 1.498a1 1 0 01.684.949V19a2 2 0 01-2 2h-1C9.716 21 3 14.284 3 6V5z" />
+                  </svg>
+                  Gọi ngay
+                </Button>
+              </a>
+              <Button variant="outline" className="w-full gap-2">
+                <svg className="h-4 w-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                  <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M8 12h.01M12 12h.01M16 12h.01M21 12c0 4.418-4.03 8-9 8a9.863 9.863 0 01-4.255-.949L3 20l1.395-3.72C3.512 15.042 3 13.574 3 12c0-4.418 4.03-8 9-8s9 3.582 9 8z" />
+                </svg>
+                Nhắn tin
+              </Button>
+
+              {agent && (
+                <div className="border-t pt-3">
+                  <p className="text-xs text-muted-foreground">Môi giới</p>
+                  {agent.agency && <p className="text-sm font-medium">{agent.agency}</p>}
+                  {listing.commissionPct != null && (
+                    <p className="text-xs text-muted-foreground">Hoa hồng: {listing.commissionPct}%</p>
+                  )}
+                </div>
+              )}
+            </CardContent>
+          </Card>
+
+          {/* AI Estimate */}
+          <AiEstimateButton listingId={listing.id} />
+
+          {/* Stats */}
+          <Card>
+            <CardContent className="pt-6">
+              <div className="grid grid-cols-3 gap-4 text-center">
+                <div>
+                  <p className="text-lg font-bold">{listing.viewCount}</p>
+                  <p className="text-xs text-muted-foreground">Lượt xem</p>
+                </div>
+                <div>
+                  <p className="text-lg font-bold">{listing.saveCount}</p>
+                  <p className="text-xs text-muted-foreground">Lượt lưu</p>
+                </div>
+                <div>
+                  <p className="text-lg font-bold">{listing.inquiryCount}</p>
+                  <p className="text-xs text-muted-foreground">Liên hệ</p>
+                </div>
+              </div>
+              {listing.publishedAt && (
+                <p className="mt-3 border-t pt-3 text-center text-xs text-muted-foreground">
+                  Đăng ngày {new Date(listing.publishedAt).toLocaleDateString('vi-VN')}
+                </p>
+              )}
+            </CardContent>
+          </Card>
+        </div>
+      </div>
+    </div>
+  );
+}
+
+function QuickStat({ icon, label, value }: { icon: string; label: string; value: string }) {
+  const icons: Record<string, React.ReactNode> = {
+    area: (
+      <svg className="h-5 w-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={1.5} d="M4 8V4m0 0h4M4 4l5 5m11-1V4m0 0h-4m4 0l-5 5M4 16v4m0 0h4m-4 0l5-5m11 5l-5-5m5 5v-4m0 4h-4" />
+      </svg>
+    ),
+    bed: (
+      <svg className="h-5 w-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={1.5} d="M3 7v11m0-7h18M3 18h18M6 14h.01M6 10a2 2 0 012-2h8a2 2 0 012 2v0H6z" />
+      </svg>
+    ),
+    bath: (
+      <svg className="h-5 w-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={1.5} d="M4 12h16M4 12a2 2 0 00-2 2v2a4 4 0 004 4h12a4 4 0 004-4v-2a2 2 0 00-2-2M4 12V7a3 3 0 013-3h1" />
+      </svg>
+    ),
+    floors: (
+      <svg className="h-5 w-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={1.5} d="M19 21V5a2 2 0 00-2-2H7a2 2 0 00-2 2v16m14 0h2m-2 0h-5m-9 0H3m2 0h5M9 7h1m-1 4h1m4-4h1m-1 4h1m-5 10v-5a1 1 0 011-1h2a1 1 0 011 1v5m-4 0h4" />
+      </svg>
+    ),
+    compass: (
+      <svg className="h-5 w-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={1.5} d="M21 12a9 9 0 11-18 0 9 9 0 0118 0z" />
+        <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={1.5} d="M9 9l3 3m0 0l3-3m-3 3V6m0 6l-3 3m3-3l3 3m-3-3v6" />
+      </svg>
+    ),
+  };
+
+  return (
+    <div className="flex items-center gap-2">
+      <div className="text-muted-foreground">{icons[icon]}</div>
+      <div>
+        <p className="text-xs text-muted-foreground">{label}</p>
+        <p className="text-sm font-semibold">{value}</p>
+      </div>
+    </div>
+  );
+}
+
+function InfoItem({ label, value }: { label: string; value: string }) {
+  return (
+    <div>
+      <p className="text-xs text-muted-foreground">{label}</p>
+      <p className="font-medium">{value}</p>
+    </div>
+  );
+}

apps/web/components/seo/json-ld.tsx

@@ -0,0 +1,188 @@
+import type { ListingDetail } from '@/lib/listings-api';
+import { PROPERTY_TYPES, TRANSACTION_TYPES } from '@/lib/validations/listings';
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+function getLabel(list: readonly { value: string; label: string }[], value: string | null) {
+  if (!value) return null;
+  return list.find((item) => item.value === value)?.label ?? value;
+}
+
+function formatPriceNumber(priceVND: string): number {
+  return Number(priceVND);
+}
+
+// ---------------------------------------------------------------------------
+// JSON-LD generator for a single listing
+// ---------------------------------------------------------------------------
+
+export function generateListingJsonLd(listing: ListingDetail, siteUrl: string) {
+  const { property } = listing;
+
+  const propertyTypeLabel = getLabel(PROPERTY_TYPES, property.propertyType) ?? property.propertyType;
+  const transactionLabel = getLabel(TRANSACTION_TYPES, listing.transactionType) ?? listing.transactionType;
+
+  const fullAddress = [property.address, property.ward, property.district, property.city]
+    .filter(Boolean)
+    .join(', ');
+
+  const images = property.media
+    .filter((m) => m.type === 'image')
+    .map((m) => m.url);
+
+  const priceNum = formatPriceNumber(listing.priceVND);
+
+  // Schema.org RealEstateListing
+  // https://schema.org/RealEstateListing
+  const jsonLd: Record<string, unknown> = {
+    '@context': 'https://schema.org',
+    '@type': 'RealEstateListing',
+    name: property.title,
+    description: property.description?.slice(0, 500),
+    url: `${siteUrl}/listings/${listing.id}`,
+    datePosted: listing.publishedAt ?? listing.createdAt,
+    ...(images.length > 0 && { image: images }),
+
+    // Offer
+    offers: {
+      '@type': 'Offer',
+      price: priceNum,
+      priceCurrency: 'VND',
+      availability: listing.status === 'ACTIVE'
+        ? 'https://schema.org/InStock'
+        : 'https://schema.org/SoldOut',
+      ...(listing.transactionType === 'RENT' && listing.rentPriceMonthly && {
+        priceSpecification: {
+          '@type': 'UnitPriceSpecification',
+          price: Number(listing.rentPriceMonthly),
+          priceCurrency: 'VND',
+          unitText: 'MONTH',
+        },
+      }),
+    },
+
+    // Location
+    contentLocation: {
+      '@type': 'Place',
+      name: fullAddress,
+      address: {
+        '@type': 'PostalAddress',
+        streetAddress: property.address,
+        addressLocality: property.district,
+        addressRegion: property.city,
+        addressCountry: 'VN',
+      },
+      ...(property.latitude != null && property.longitude != null && {
+        geo: {
+          '@type': 'GeoCoordinates',
+          latitude: property.latitude,
+          longitude: property.longitude,
+        },
+      }),
+    },
+
+    // Additional property details via additionalProperty
+    additionalProperty: [
+      {
+        '@type': 'PropertyValue',
+        name: 'Loại BDS',
+        value: propertyTypeLabel,
+      },
+      {
+        '@type': 'PropertyValue',
+        name: 'Loại giao dich',
+        value: transactionLabel,
+      },
+      {
+        '@type': 'PropertyValue',
+        name: 'Dien tich',
+        value: `${property.areaM2} m²`,
+        unitCode: 'MTK',
+      },
+      ...(property.bedrooms != null
+        ? [{
+            '@type': 'PropertyValue' as const,
+            name: 'Phong ngu',
+            value: property.bedrooms,
+          }]
+        : []),
+      ...(property.bathrooms != null
+        ? [{
+            '@type': 'PropertyValue' as const,
+            name: 'Phong tam',
+            value: property.bathrooms,
+          }]
+        : []),
+      ...(property.floors != null
+        ? [{
+            '@type': 'PropertyValue' as const,
+            name: 'So tang',
+            value: property.floors,
+          }]
+        : []),
+    ],
+  };
+
+  return jsonLd;
+}
+
+// ---------------------------------------------------------------------------
+// BreadcrumbList JSON-LD
+// ---------------------------------------------------------------------------
+
+export function generateBreadcrumbJsonLd(
+  items: { name: string; url: string }[],
+) {
+  return {
+    '@context': 'https://schema.org',
+    '@type': 'BreadcrumbList',
+    itemListElement: items.map((item, index) => ({
+      '@type': 'ListItem',
+      position: index + 1,
+      name: item.name,
+      item: item.url,
+    })),
+  };
+}
+
+// ---------------------------------------------------------------------------
+// Website (Organization) JSON-LD — for the root layout
+// ---------------------------------------------------------------------------
+
+export function generateWebsiteJsonLd(siteUrl: string) {
+  return {
+    '@context': 'https://schema.org',
+    '@type': 'WebSite',
+    name: 'GoodGo',
+    url: siteUrl,
+    description: 'Nen tang bat dong san thong minh tai Viet Nam',
+    potentialAction: {
+      '@type': 'SearchAction',
+      target: {
+        '@type': 'EntryPoint',
+        urlTemplate: `${siteUrl}/search?q={search_term_string}`,
+      },
+      'query-input': 'required name=search_term_string',
+    },
+    inLanguage: ['vi', 'en'],
+  };
+}
+
+// ---------------------------------------------------------------------------
+// React component that renders <script type="application/ld+json">
+// ---------------------------------------------------------------------------
+
+interface JsonLdProps {
+  data: Record<string, unknown> | Record<string, unknown>[];
+}
+
+export function JsonLd({ data }: JsonLdProps) {
+  return (
+    <script
+      type="application/ld+json"
+      dangerouslySetInnerHTML={{ __html: JSON.stringify(data) }}
+    />
+  );
+}