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/online/mock-service.ts

@@ -18,6 +18,7 @@ import {
 } from "./service";
 import {
   AVATARS,
+  AppNotification,
   AuthSession,
   ChatMessage,
   Conversation,
@@ -463,6 +464,40 @@ export class MockOnlineService implements OnlineService {
     for (const cb of this.reactionCbs) cb(0, reaction);
   }
 
+  /* --------------------------- notifications ------------------------- */
+
+  private notifCbs = new Set<(n: AppNotification) => void>();
+  private notifTimer: ReturnType<typeof setInterval> | null = null;
+
+  onNotification(cb: (n: AppNotification) => void): Unsubscribe {
+    this.notifCbs.add(cb);
+    if (this.notifTimer == null) {
+      const samples: Array<Pick<AppNotification, "kind" | "titleFa" | "titleEn" | "icon">> = [
+        { kind: "system", titleFa: "یک دوست آنلاین شد", titleEn: "A friend is online", icon: "👋" },
+        { kind: "system", titleFa: "مسابقه‌ی امروز شروع شد", titleEn: "Today's event is live", icon: "🏆" },
+        { kind: "invite", titleFa: "یک نفر دنبال هم‌بازیه", titleEn: "Someone is looking for a partner", icon: "🎴" },
+      ];
+      this.notifTimer = setInterval(() => {
+        if (this.notifCbs.size === 0) return;
+        const s = pick(samples);
+        const n: AppNotification = {
+          id: rid("ntf"),
+          ts: Date.now(),
+          read: false,
+          ...s,
+        };
+        for (const c of this.notifCbs) c(n);
+      }, 35000);
+    }
+    return () => {
+      this.notifCbs.delete(cb);
+      if (this.notifCbs.size === 0 && this.notifTimer) {
+        clearInterval(this.notifTimer);
+        this.notifTimer = null;
+      }
+    };
+  }
+
   // The mock drives the game locally (game-store), so these are no-ops.
   readonly live = false;
   onState(): Unsubscribe { return () => {}; }