added push notifications

frontend/app/_layout.tsx

@@ -1,13 +1,62 @@
 import "../globals.css";
-import { Stack } from "expo-router";
-import {AuthProvider} from "@/context/AuthContext";
-import {SafeAreaProvider} from "react-native-safe-area-context";
+import { useEffect } from 'react';
+import { Stack } from 'expo-router';
+import { SafeAreaProvider } from 'react-native-safe-area-context';
+import {
+    getMessaging,
+    onMessage,
+    onNotificationOpenedApp,
+    getInitialNotification,
+} from '@react-native-firebase/messaging';
+import { registerDeviceToken, listenForTokenRefresh } from '@/services/notifications';
+import { AuthProvider, useAuth } from "@/context/AuthContext";
+import Toast from 'react-native-toast-message';
+
+function NotificationSetup() {
+    const { user, loading } = useAuth();
+
+    useEffect(() => {
+        if (loading || !user) return;
+
+        registerDeviceToken(user.token);
+
+        const messaging = getMessaging();
+
+        const unsubRefresh    = listenForTokenRefresh(user.token);
+        const unsubForeground = onMessage(messaging, async (msg) => {
+            console.log('Foreground notification:', msg);
+            Toast.show({
+                type: 'info',
+                text1: msg.notification?.title ?? 'New Notification',
+                position: 'top',
+                visibilityTime: 4000,
+            });
+        });
+
+        onNotificationOpenedApp(messaging, (msg) => {
+            console.log('Opened from background:', msg);
+        });
+
+        getInitialNotification(messaging).then((msg) => {
+            if (msg) console.log('Opened from quit state:', msg);
+        });
+
+        return () => {
+            unsubRefresh();
+            unsubForeground();
+        };
+    }, [user, loading]);
+
+    return null;
+}
 
 export default function RootLayout() {
     return (
         <AuthProvider>
             <SafeAreaProvider>
+                <NotificationSetup />
                 <Stack screenOptions={{ headerShown: false }} />
+                <Toast />
             </SafeAreaProvider>
         </AuthProvider>
     );