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

config/environments/development.rb

@@ -34,6 +34,13 @@ Rails.application.configure do
   # Don't care if the mailer can't send.
   config.action_mailer.raise_delivery_errors = false
 
+  # Configure mailer to use localhost:1025 for development
+  config.action_mailer.delivery_method = :smtp
+  config.action_mailer.smtp_settings = {
+    address: "localhost",
+    port: 1025
+  }
+
   # Make template changes take effect immediately.
   config.action_mailer.perform_caching = false