feat: fix gesture back to prevent going bakc to login

frontend/lib/screens/home_screen.dart

@@ -10,42 +10,38 @@ class HomeScreen extends StatefulWidget {
 
 class _HomeScreenState extends State<HomeScreen> {
   int _currentIndex = 0;
-  
+
-  final List<Widget> _pages = [
+  final List<Widget> _pages = [FeedPage(), InvitationsPage(), ProfilePage()];
-    FeedPage(),
-    InvitationsPage(),
-    ProfilePage(),
-  ];
 
   @override
   Widget build(BuildContext context) {
-    return Scaffold(
+    return WillPopScope(
-      body: _pages[_currentIndex],
+      onWillPop: () async {
-      bottomNavigationBar: BottomNavigationBar(
+        // Prevent going back to authentication screens
-        currentIndex: _currentIndex,
+        return false;
-        onTap: (index) {
+      },
-          setState(() {
+      child: Scaffold(
-            _currentIndex = index;
+        body: _pages[_currentIndex],
-          });
+        bottomNavigationBar: BottomNavigationBar(
-        },
+          currentIndex: _currentIndex,
-        type: BottomNavigationBarType.fixed,
+          onTap: (index) {
-        selectedItemColor: Color(0xFF6A4C93),
+            setState(() {
-        unselectedItemColor: Colors.grey,
+              _currentIndex = index;
-        items: [
+            });
-          BottomNavigationBarItem(
+          },
-            icon: Icon(Icons.home),
+          type: BottomNavigationBarType.fixed,
-            label: 'Feed',
+          selectedItemColor: Color(0xFF6A4C93),
-          ),
+          unselectedItemColor: Colors.grey,
-          BottomNavigationBarItem(
+          items: [
-            icon: Icon(Icons.mail),
+            BottomNavigationBarItem(icon: Icon(Icons.home), label: 'Feed'),
-            label: 'Invitations',
+            BottomNavigationBarItem(
-          ),
+              icon: Icon(Icons.mail),
-          BottomNavigationBarItem(
+              label: 'Invitations',
-            icon: Icon(Icons.person),
+            ),
-            label: 'Profile',
+            BottomNavigationBarItem(icon: Icon(Icons.person), label: 'Profile'),
-          ),
+          ],
-        ],
+        ),
       ),
     );
   }
-}
+}