feat: Phase 1 critical gaps — gamification API, Razorpay checkout, Google OAuth, notifications

- Fix gamification endpoints to use Node.js server (app.eventifyplus.com)
- Replace 6 mock gamification methods with real API calls (dashboard, leaderboard, shop, redeem, submit)
- Add booking models, service, payment service (Razorpay), checkout provider
- Add 3-step CheckoutScreen with Razorpay native modal integration
- Add Google OAuth login (Flutter + Django backend)
- Add full notifications system (Django model + 3 endpoints + Flutter UI)
- Register CheckoutProvider, NotificationProvider in main.dart MultiProvider
- Wire notification bell in HomeScreen app bar
- Add razorpay_flutter ^1.3.7 and google_sign_in ^6.2.2 packages

lib/screens/home_screen.dart

@@ -20,6 +20,8 @@ import 'package:geocoding/geocoding.dart';
 import 'package:flutter_svg/flutter_svg.dart';
 import 'package:provider/provider.dart';
 import '../features/gamification/providers/gamification_provider.dart';
+import '../features/notifications/widgets/notification_bell.dart';
+import '../features/notifications/providers/notification_provider.dart';
 
 class HomeScreen extends StatefulWidget {
   const HomeScreen({Key? key}) : super(key: key);
@@ -126,6 +128,11 @@ class _HomeScreenState extends State<HomeScreen> with SingleTickerProviderStateM
         ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text(userFriendlyError(e))));
       }
     }
+
+    // Refresh notification badge count (fire-and-forget)
+    if (mounted) {
+      context.read<NotificationProvider>().refreshUnreadCount();
+    }
   }
 
   Future<void> _reverseGeocodeAndSave(double lat, double lng, SharedPreferences prefs) async {
@@ -438,12 +445,7 @@ class _HomeScreenState extends State<HomeScreen> with SingleTickerProviderStateM
             children: [
               RepaintBoundary(child: _buildHomeContent()), // index 0
               const RepaintBoundary(child: CalendarScreen()), // index 1
-              RepaintBoundary(
-                child: ChangeNotifierProvider(
-                  create: (_) => GamificationProvider(),
-                  child: const ContributeScreen(),
-                ),
-              ), // index 2 (full page, scrollable)
+              const RepaintBoundary(child: ContributeScreen()), // index 2 (full page, scrollable)
               const RepaintBoundary(child: ProfileScreen()), // index 3
             ],
           ),
@@ -1221,18 +1223,25 @@ class _HomeScreenState extends State<HomeScreen> with SingleTickerProviderStateM
                     ),
                   ),
                 ),
-                GestureDetector(
-                  onTap: _openEventSearch,
-                  child: Container(
-                    width: 48,
-                    height: 48,
-                    decoration: BoxDecoration(
-                      color: Colors.white.withOpacity(0.15),
-                      shape: BoxShape.circle,
-                      border: Border.all(color: Colors.white.withOpacity(0.2)),
+                Row(
+                  mainAxisSize: MainAxisSize.min,
+                  children: [
+                    const NotificationBell(),
+                    const SizedBox(width: 8),
+                    GestureDetector(
+                      onTap: _openEventSearch,
+                      child: Container(
+                        width: 48,
+                        height: 48,
+                        decoration: BoxDecoration(
+                          color: Colors.white.withOpacity(0.15),
+                          shape: BoxShape.circle,
+                          border: Border.all(color: Colors.white.withOpacity(0.2)),
+                        ),
+                        child: const Icon(Icons.search, color: Colors.white, size: 24),
+                      ),
                     ),
-                    child: const Icon(Icons.search, color: Colors.white, size: 24),
-                  ),
+                  ],
                 ),
               ],
             ),