feat(notification): integrate expo-notifications for permission handling and deep linking

- Add expo-notifications dependency and configure with JPush plugin
- Request notification permission on app launch for iOS/Android
- Handle notification taps to navigate to chat or notifications screen
- Add UI to check and request system notification permission in settings
- Refactor background sync: WebSocket disconnects in background, JPush handles push
- Add checkNotificationPermission() and requestNotificationPermission() to jpushService

app/_layout.tsx

@@ -128,6 +128,8 @@ function SessionGate({ children }: { children: React.ReactNode }) {
 
 function NotificationBootstrap() {
   const appState = useRef<AppStateStatus>(AppState.currentState);
+  const permissionRequested = useRef(false);
+  const router = useRouter();
 
   useEffect(() => {
     const initNotifications = async () => {
@@ -145,9 +147,24 @@ function NotificationBootstrap() {
         appState.current = nextAppState;
       });
 
-      // Listen for JPush notification taps
+      // Listen for JPush notification taps — navigate to the relevant screen
       jpushService.onNotification((message) => {
-        console.log('[NotificationBootstrap] JPush notification tapped:', message);
+        console.log('[NotificationBootstrap] JPush notification:', message.notificationEventType, message);
+        if (message.notificationEventType !== 'notificationOpened') return;
+
+        const extras = message.extras || {};
+        const notifType = extras.notification_type || message.notificationType;
+
+        if (notifType === 'chat_message' && extras.conversation_id) {
+          const isGroup = extras.conversation_type === 'group';
+          router.push(
+            `/chat/${encodeURIComponent(extras.conversation_id)}${
+              isGroup ? '?isGroupChat=1' : extras.sender_id ? `?userId=${encodeURIComponent(extras.sender_id)}` : ''
+            }`
+          );
+        } else {
+          router.push('/messages/notifications');
+        }
       });
 
       return () => {
@@ -155,7 +172,24 @@ function NotificationBootstrap() {
       };
     };
 
+    const requestPermissionOnLaunch = async () => {
+      if (permissionRequested.current) return;
+      permissionRequested.current = true;
+
+      if (Platform.OS === 'web') return;
+
+      try {
+        const hasPermission = await jpushService.checkNotificationPermission();
+        if (!hasPermission) {
+          await jpushService.requestNotificationPermission();
+        }
+      } catch (error) {
+        console.warn('[NotificationBootstrap] request permission on launch failed:', error);
+      }
+    };
+
     initNotifications();
+    requestPermissionOnLaunch();
   }, []);
 
   return null;