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/features/notifications/widgets/notification_tile.dart

@@ -0,0 +1,94 @@
+// lib/features/notifications/widgets/notification_tile.dart
+
+import 'package:flutter/material.dart';
+import '../models/notification_model.dart';
+
+class NotificationTile extends StatelessWidget {
+  final NotificationModel notification;
+  final VoidCallback? onTap;
+
+  const NotificationTile({Key? key, required this.notification, this.onTap}) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return InkWell(
+      onTap: onTap,
+      child: Container(
+        color: notification.isRead ? Colors.transparent : const Color(0xFFF0F4FF),
+        padding: const EdgeInsets.symmetric(horizontal: 20, vertical: 14),
+        child: Row(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            _buildIcon(),
+            const SizedBox(width: 14),
+            Expanded(
+              child: Column(
+                crossAxisAlignment: CrossAxisAlignment.start,
+                children: [
+                  Text(
+                    notification.title,
+                    style: TextStyle(
+                      fontWeight: notification.isRead ? FontWeight.w400 : FontWeight.w600,
+                      fontSize: 14,
+                    ),
+                    maxLines: 1,
+                    overflow: TextOverflow.ellipsis,
+                  ),
+                  const SizedBox(height: 4),
+                  Text(
+                    notification.message,
+                    style: TextStyle(color: Colors.grey.shade600, fontSize: 13),
+                    maxLines: 2,
+                    overflow: TextOverflow.ellipsis,
+                  ),
+                  const SizedBox(height: 6),
+                  Text(
+                    _timeAgo(notification.createdAt),
+                    style: TextStyle(color: Colors.grey.shade400, fontSize: 12),
+                  ),
+                ],
+              ),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  Widget _buildIcon() {
+    final config = _typeConfig(notification.type);
+    return Container(
+      width: 40,
+      height: 40,
+      decoration: BoxDecoration(
+        color: config.color.withOpacity(0.15),
+        shape: BoxShape.circle,
+      ),
+      child: Icon(config.icon, color: config.color, size: 20),
+    );
+  }
+
+  static _TypeConfig _typeConfig(String type) {
+    switch (type) {
+      case 'event':   return _TypeConfig(Colors.blue, Icons.event);
+      case 'promo':   return _TypeConfig(Colors.green, Icons.local_offer);
+      case 'booking': return _TypeConfig(Colors.orange, Icons.confirmation_number);
+      default:        return _TypeConfig(Colors.grey, Icons.info_outline);
+    }
+  }
+
+  static String _timeAgo(DateTime dt) {
+    final diff = DateTime.now().difference(dt);
+    if (diff.inMinutes < 1) return 'Just now';
+    if (diff.inMinutes < 60) return '${diff.inMinutes}m ago';
+    if (diff.inHours < 24) return '${diff.inHours}h ago';
+    if (diff.inDays < 7) return '${diff.inDays}d ago';
+    return '${dt.day}/${dt.month}/${dt.year}';
+  }
+}
+
+class _TypeConfig {
+  final Color color;
+  final IconData icon;
+  const _TypeConfig(this.color, this.icon);
+}