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.json

@@ -58,7 +58,8 @@
         "android.permission.READ_MEDIA_VIDEO",
         "android.permission.READ_MEDIA_AUDIO",
         "android.permission.ACCESS_NETWORK_STATE",
-        "android.permission.ACCESS_WIFI_STATE"
+        "android.permission.ACCESS_WIFI_STATE",
+        "android.permission.POST_NOTIFICATIONS"
       ]
     },
     "web": {
@@ -136,6 +137,14 @@
         }
       ],
       "expo-font",
+      [
+        "expo-notifications",
+        {
+          "color": "#E6F4FE",
+          "defaultChannel": "default",
+          "enableBackgroundRemoteNotifications": true
+        }
+      ],
       [
         "./plugins/withJPush",
         {