feat: implement flash messages system with auto-dismiss notifications

- Add flash message helper and styles for consistent notifications
- Replace Devise error messages with flash-based notifications
- Add dashboard page with event statistics
- Configure SMTP settings for development and production
- Update authentication controllers to use flash messages
- Add JavaScript controller for auto-dismiss functionality

db/seeds.rb

@@ -44,7 +44,7 @@ parties_data = [
     start_time: 1.day.from_now,
     end_time: 1.day.from_now + 6.hours,
     featured: true,
-    image: "https://images.unsplash.com/photo-1506157786151-b84b9d3d78d8?ixlib=rb-4.0.3&auto=format&fit=crop&w=800&q=80",
+    image: "https://fastly.picsum.photos/id/407/300/200.jpg?hmac=9EhoXMZ1QdwJue90vzxcjBg2YzsZsAWCjJ7oxOhtcU0",
     user: users.first
   },
   {