Replace Alpine.js with Stimulus controller for header navigation

- Create header_controller.js to handle mobile menu and user dropdown
- Replace Alpine.js directives with Stimulus data attributes in header component
- Add proper event handling for click outside to close menus
- Maintain all existing functionality with improved code consistency

app/javascript/controllers/index.js

@@ -2,10 +2,8 @@
 // Run that command whenever you add a new controller or create them with
 // ./bin/rails generate stimulus controllerName
 
-// Import the main Stimulus application
 import { application } from "./application"
 
-// Import all controllers
 import LogoutController from "./logout_controller";
 application.register("logout", LogoutController);
 
@@ -18,6 +16,9 @@ application.register("flash-message", FlashMessageController);
 import TicketSelectionController from "./ticket_selection_controller"
 application.register("ticket-selection", TicketSelectionController);
 
+import HeaderController from "./header_controller"
+application.register("header", HeaderController);
+