Add in-app + real-time notifications (SignalR/mock, Iran-friendly)

- AppNotification + OnlineService.onNotification (hub event + mock periodic) —
  no FCM/APNs (blocked in Iran); uses the existing realtime channel
- notification-store + pushNotification(); 🔔 bell with unread badge in TopBar,
  notifications screen, global toaster (plays notify sfx)
- Wired events: daily reward, post-match achievements, friend requests
- Closed-app push (Pushe/Najva/Chabok) noted as a later step (needs provider keys)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/lib/ui-store.ts

@@ -13,16 +13,17 @@ export type Screen =
   | "leaderboard"
   | "shop"
   | "chat"
+  | "notifications"
   | "game"; // the table (used for both ai + online)
 
 const ALL_SCREENS: Screen[] = [
   "home", "auth", "profile", "friends", "online",
-  "room", "matchmaking", "leaderboard", "shop", "chat", "game",
+  "room", "matchmaking", "leaderboard", "shop", "chat", "notifications", "game",
 ];
 
 /** Screens safe to restore from a URL on a cold load (no transient state needed). */
 export const STATIC_SCREENS: Screen[] = [
-  "home", "auth", "profile", "friends", "online", "leaderboard", "shop",
+  "home", "auth", "profile", "friends", "online", "leaderboard", "shop", "notifications",
 ];
 
 export function screenFromHash(): Screen {