feat: real Halal Monitor via Overpass API + user-contributed yellow markers

- Replace hardcoded KL mock data with live OpenStreetMap Overpass API
- Support 15+ major cities worldwide (London, Dubai, Tokyo, NY, etc.)
- Bounding-box queries (faster than radius search)
- HTTP/1.1 fix for Overpass Apache compat
- Nominatim geocoding for city search
- 6-hour file-based cache per grid cell
- 3-mirror Overpass fallback with retry on timeout
- User-contributed places with yellow (⭐) markers
- 'Add Place' modal with name/type/address/notes form
- Map tap-to-pin coordinates for new places
- Delete own submissions from detail modal
- Prisma UserPlace model + API routes

Closes: Halal Monitor showing only KL data

prisma/schema.prisma

@@ -40,6 +40,7 @@ model User {
   cashouts       CashoutRequest[]
   halalBookmarks HalalBookmark[]
   halalUsage     HalalUsage?
+  userPlaces     UserPlace[]
   ownedGroups    Group[]           @relation("GroupOwner")
   groupMemberships GroupMember[]
   forumThreads   ForumThread[]
@@ -241,6 +242,23 @@ model HalalUsage {
   periodEnd    DateTime?
 }
 
+model UserPlace {
+  id        String   @id @default(cuid())
+  userId    String
+  user      User     @relation(fields: [userId], references: [id])
+  name      String
+  address   String
+  lat       Float
+  lng       Float
+  type      String   // "mosque" | "restaurant" | "cafe"
+  notes     String?
+  createdAt DateTime @default(now())
+  updatedAt DateTime @updatedAt
+
+  @@index([userId])
+  @@index([lat, lng])
+}
+
 model Notification {
   id        String   @id @default(cuid())
   userId    String