feat(listings): Mapbox location picker in create + edit forms

User feedback: typing lat/lng by hand is painful — wire a real map
picker.

New component apps/web/components/map/location-picker.tsx:
- Mapbox map with theme-synced style (uses useMapboxStyle).
- Draggable primary marker (custom pin, inner-wrapped so Mapbox's
  translate isn't clobbered — follows the hover-fix pattern we shipped
  last commit).
- Click anywhere on the map → marker jumps + onChange fires.
- Dragend → onChange fires.
- Search box using Mapbox Geocoding API
  (/geocoding/v5/mapbox.places) scoped to country=vn, language=vi,
  limit=5, debounced 350ms with AbortController. Clicking a suggestion
  centers the map + fills the resolved { address, ward, district,
  city } from feature.context.
- Graceful fallback when NEXT_PUBLIC_MAPBOX_TOKEN is missing.
- Inline help "Nhấp vào bản đồ hoặc kéo pin để chọn vị trí".

StepLocation (listing-form-steps.tsx):
- New optional `setValue` + `watch` props. When both are passed the
  picker renders and wires lat/lng (+ address/ward/district/city from
  geocoder) into the form. Without them, the Step falls back to the
  manual-only layout (kept for callers that don't want the picker).
- Dynamic-import the picker with ssr:false so mapbox-gl stays out of
  the server bundle.

Wired into:
- /listings/new page — picker enabled on Step 2 (Vị trí).
- /listings/[id]/edit page — picker enabled on the Location tab, with
  latitude/longitude now hydrated from property.latitude/longitude.

Test fixture update: listing-form-steps.spec.tsx no longer asserts the
placeholder string — instead verifies the lat/lng inputs still render
when the picker is absent (setValue not supplied), matching the new
opt-in contract.

Verification
- Typecheck clean across touched files.
- 624 / 624 web tests pass.
- Preview smoke: /listings/<id>/edit → Vị trí tab renders map +
  draggable pin + search, lat/lng prefilled from listing data.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/components/listings/listing-form-steps.tsx

@@ -1,6 +1,7 @@
 'use client';
 
-import type { UseFormRegister, FieldErrors } from 'react-hook-form';
+import dynamic from 'next/dynamic';
+import type { UseFormRegister, UseFormSetValue, UseFormWatch, FieldErrors } from 'react-hook-form';
 import { Input } from '@/components/ui/input';
 import { Label } from '@/components/ui/label';
 import { Select } from '@/components/ui/select';
@@ -14,11 +15,34 @@ import {
   type CreateListingFormData,
 } from '@/lib/validations/listings';
 
+// Mapbox picker is client-only + imports `mapbox-gl` which pulls WebGL
+// utilities — dynamic-import with ssr:false to keep it out of the server
+// bundle.
+const LocationPicker = dynamic(
+  () => import('@/components/map/location-picker').then((m) => m.LocationPicker),
+  {
+    ssr: false,
+    loading: () => (
+      <div className="flex h-[320px] items-center justify-center rounded-lg border bg-muted text-sm text-muted-foreground">
+        Đang tải bản đồ...
+      </div>
+    ),
+  },
+);
+
 interface StepProps {
   register: UseFormRegister<CreateListingFormData>;
   errors: FieldErrors<CreateListingFormData>;
 }
 
+interface StepLocationProps extends StepProps {
+  /** Optional — when provided, StepLocation renders the Mapbox picker and
+   *  writes latitude/longitude (+ auto-fills address/ward/district/city on
+   *  geocoder pick) into the form state. */
+  setValue?: UseFormSetValue<CreateListingFormData>;
+  watch?: UseFormWatch<CreateListingFormData>;
+}
+
 function FieldError({ message }: { message?: string }) {
   if (!message) return null;
   return <p className="mt-1 text-xs text-destructive">{message}</p>;
@@ -81,11 +105,38 @@ export function StepBasicInfo({ register, errors }: StepProps) {
 
 // ─── Step 2: Location ────────────────────────────────────
 
-export function StepLocation({ register, errors }: StepProps) {
+export function StepLocation({ register, errors, setValue, watch }: StepLocationProps) {
+  // Watch lat/lng so the picker stays in sync when the user edits the text
+  // inputs manually.
+  const latStr = watch?.('latitude') ?? '';
+  const lngStr = watch?.('longitude') ?? '';
+  const latNum = latStr ? Number(latStr) : null;
+  const lngNum = lngStr ? Number(lngStr) : null;
+  const latValid = latNum != null && Number.isFinite(latNum) && latNum >= -90 && latNum <= 90;
+  const lngValid = lngNum != null && Number.isFinite(lngNum) && lngNum >= -180 && lngNum <= 180;
+
   return (
     <div className="space-y-4">
       <h3 className="text-lg font-semibold">Vị trí</h3>
 
+      {setValue && (
+        <LocationPicker
+          lat={latValid ? latNum : null}
+          lng={lngValid ? lngNum : null}
+          onChange={(coords, resolved) => {
+            setValue('latitude', coords.lat.toFixed(6), { shouldValidate: true, shouldDirty: true });
+            setValue('longitude', coords.lng.toFixed(6), { shouldValidate: true, shouldDirty: true });
+            if (resolved) {
+              if (resolved.address) setValue('address', resolved.address, { shouldDirty: true });
+              if (resolved.ward) setValue('ward', resolved.ward, { shouldDirty: true });
+              if (resolved.district) setValue('district', resolved.district, { shouldDirty: true });
+              if (resolved.city) setValue('city', resolved.city, { shouldDirty: true });
+            }
+          }}
+          height="360px"
+        />
+      )}
+
       <div>
         <Label htmlFor="address">Địa chỉ *</Label>
         <Input id="address" placeholder="Số nhà, tên đường" {...register('address')} />
@@ -134,10 +185,6 @@ export function StepLocation({ register, errors }: StepProps) {
           <FieldError message={errors.longitude?.message} />
         </div>
       </div>
-
-      <div className="rounded-lg border border-dashed p-6 text-center text-sm text-muted-foreground">
-        Bản đồ chọn vị trí sẽ được tích hợp trong phiên bản tiếp theo
-      </div>
     </div>
   );
 }