fix(maps): reduce Google Places API quota usage with persistent caching

P0 — stop the bleeding:
- Honor place.image_url in MapView and TripPlannerPage to skip redundant fetchPhoto calls
- Trim Place Details field mask (drop reviews/editorialSummary from default; new getPlaceDetailsExpanded for inspector)
- Admin toggle places_photos_enabled (default ON) to kill Google photo fetches under quota pressure; Wikimedia unaffected
- Return { photoUrl: null } instead of 204 so client handles disabled state cleanly

P1 — structural fix:
- New placePhotoCache service: persistent disk cache at uploads/photos/google/<sha1>.jpg, atomic writes, stampede dedup via in-flight Map
- Migrations 105-107: google_place_photo_meta table, place_details_cache table, backfill signed Google URLs to stable proxy URLs
- getPlacePhoto rewrites to fetch image bytes directly, store on disk, return /api/maps/place-photo/:id/bytes proxy URL
- Stable proxy URLs written to places.image_url — survive container restarts, no expiry
- New GET /api/maps/place-photo/:placeId/bytes route serving cached files with long-lived Cache-Control
- Place Details DB row cache with 7-day TTL; ?refresh=1 escape hatch
- photoService fast-path: proxy URLs bypass the mapsApi round-trip and go straight to urlToBase64

Bug fixes:
- MapView now requests base64 thumbs for places with proxy image_url (markers were showing color fallback)
- createPlaceIcon accepts /api/maps/place-photo/ URLs as interim fallback while thumb generates
- setSelectedAssignmentId ReferenceError in mobile day-detail handler (use selectAssignment)
- Remove redundant decodeURIComponent on already-decoded Express route param
- Use SHA1 hash for disk filenames to prevent coords:lat:lng pseudo-ID collisions
- Add checkSsrf guard to Wikimedia byte fetch
- Tighten migration 107 LIKE filter to avoid rewriting manually-pasted Google image URLs
- Validate enabled is boolean on PUT /admin/places-photos
- Drop aggressive iconCache.clear() on every thumb arrival

Observability:
- googleFetch() wrapper counts and debug-logs every outbound Google API call with running total

server/src/services/adminService.ts

@@ -459,6 +459,18 @@ export function updateBagTracking(enabled: boolean) {
   return { enabled: !!enabled };
 }
 
+// ── Places Photos ─────────────────────────────────────────────────────────
+
+export function getPlacesPhotos() {
+  const row = db.prepare("SELECT value FROM app_settings WHERE key = 'places_photos_enabled'").get() as { value: string } | undefined;
+  return { enabled: row?.value !== 'false' };
+}
+
+export function updatePlacesPhotos(enabled: boolean) {
+  db.prepare("INSERT OR REPLACE INTO app_settings (key, value) VALUES ('places_photos_enabled', ?)").run(enabled ? 'true' : 'false');
+  return { enabled: !!enabled };
+}
+
 // ── Collab Features ───────────────────────────────────────────────────────
 
 const COLLAB_FEATURE_KEYS = ['collab_chat_enabled', 'collab_notes_enabled', 'collab_polls_enabled', 'collab_whatsnext_enabled'] as const;