feat(agents): add public agent profile page at /agents/[id]

Implements a public-facing agent profile page with:
- Backend: new GET /agents/:agentId/profile public API endpoint with
  agent info, active listings, quality score, and review stats
- Frontend: server-rendered profile page with generateMetadata for SEO,
  JSON-LD structured data (RealEstateAgent schema), breadcrumbs
- Agent profile displays bio, service areas, quality score gauge,
  active listing cards, reviews with star ratings, and contact CTA
- Mobile responsive layout with sticky contact sidebar on desktop
- Vietnamese UI text throughout, consistent with existing patterns

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

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

@@ -1,3 +1,4 @@
+import type { AgentPublicProfile } from '@/lib/agents-api';
 import type { ListingDetail } from '@/lib/listings-api';
 import { PROPERTY_TYPES, TRANSACTION_TYPES } from '@/lib/validations/listings';
 
@@ -170,6 +171,46 @@ export function generateWebsiteJsonLd(siteUrl: string) {
   };
 }
 
+// ---------------------------------------------------------------------------
+// Agent profile JSON-LD (RealEstateAgent)
+// ---------------------------------------------------------------------------
+
+export function generateAgentJsonLd(agent: AgentPublicProfile, siteUrl: string) {
+  const jsonLd: Record<string, unknown> = {
+    '@context': 'https://schema.org',
+    '@type': 'RealEstateAgent',
+    name: agent.fullName,
+    url: `${siteUrl}/agents/${agent.id}`,
+    description: agent.bio ?? `Môi giới bất động sản tại GoodGo`,
+    ...(agent.avatarUrl && { image: agent.avatarUrl }),
+    telephone: agent.phone,
+    ...(agent.email && { email: agent.email }),
+    ...(agent.agency && {
+      worksFor: {
+        '@type': 'RealEstateAgent',
+        name: agent.agency,
+      },
+    }),
+    ...(agent.serviceAreas.length > 0 && {
+      areaServed: agent.serviceAreas.map((area) => ({
+        '@type': 'AdministrativeArea',
+        name: area,
+      })),
+    }),
+    ...(agent.totalReviews > 0 && {
+      aggregateRating: {
+        '@type': 'AggregateRating',
+        ratingValue: agent.avgReviewRating,
+        reviewCount: agent.totalReviews,
+        bestRating: 5,
+        worstRating: 1,
+      },
+    }),
+  };
+
+  return jsonLd;
+}
+
 // ---------------------------------------------------------------------------
 // React component that renders <script type="application/ld+json">
 // ---------------------------------------------------------------------------