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

app/helpers/application_helper.rb

@@ -1,5 +1,9 @@
 module ApplicationHelper
+  # Convert prince from cents to float
   def format_price(cents)
     (cents.to_f / 100).round(2)
   end
+
+  # Include flash message helpers
+  include FlashMessagesHelper
 end