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

src/services/notification/jpushService.ts

@@ -1,5 +1,6 @@
 import { Platform, NativeModules } from 'react-native';
 import { pushService } from './pushService';
+import * as Notifications from 'expo-notifications';
 
 type JPushNotificationMessage = {
   messageID: string;
@@ -305,6 +306,35 @@ class JPushService {
     }
   }
 
+  /**
+   * 请求通知权限（使用 expo-notifications，统一处理 iOS/Android）
+   */
+  async requestNotificationPermission(): Promise<boolean> {
+    if (Platform.OS === 'web') return false;
+
+    try {
+      const { status } = await Notifications.requestPermissionsAsync();
+      return status === 'granted';
+    } catch (error) {
+      console.warn('[JPush] request notification permission failed:', error);
+      return false;
+    }
+  }
+
+  /**
+   * 检查通知权限是否已开启
+   */
+  async checkNotificationPermission(): Promise<boolean> {
+    if (Platform.OS === 'web') return false;
+
+    try {
+      const { status } = await Notifications.getPermissionsAsync();
+      return status === 'granted';
+    } catch {
+      return false;
+    }
+  }
+
   cleanup(): void {
     this.isInitialized = false;
     this.registrationID = null;