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

package.json

@@ -37,6 +37,7 @@
     "expo-intent-launcher": "~55.0.9",
     "expo-linear-gradient": "^55.0.8",
     "expo-media-library": "~55.0.9",
+    "expo-notifications": "~55.0.0",
     "expo-router": "^55.0.4",
     "expo-sqlite": "~55.0.10",
     "expo-status-bar": "~55.0.4",