fix push notification delivery on android

frontend/app/_layout.tsx

@@ -7,21 +7,15 @@ import {
     onMessage,
     onNotificationOpenedApp,
     getInitialNotification,
-    setBackgroundMessageHandler,
 } from '@react-native-firebase/messaging';
-import { registerDeviceToken, listenForTokenRefresh, displayLocalNotification } from '@/services/notifications';
+import { registerDeviceToken, listenForTokenRefresh } from '@/services/notifications';
 import { AuthProvider, useAuth } from "@/context/AuthContext";
 import { useUpdatecheck } from '@/hooks/useUpdatecheck';
 import { UpdatePrompt } from '@/components/UpdatePrompt';
 import Toast from 'react-native-toast-message';
 
-// Registered at module scope so it's installed as soon as this entry file
-// loads, which is required for it to fire while the app is backgrounded/killed.
-setBackgroundMessageHandler(getMessaging(), async (remoteMessage) => {
-    const title = remoteMessage.data?.title as string | undefined;
-    const body = remoteMessage.data?.body as string | undefined;
-    await displayLocalNotification(title, body);
-});
+// The FCM background handler now lives in index.js (registered before this
+// module loads) so it fires reliably while the app is backgrounded/killed.
 
 function NotificationSetup() {
     const { user, loading } = useAuth();