- Moved `showError`, `showStatus`, `showSuccess`, and `updateNotificationPortalVisibility` logic to `js/ui/notificationController.js`.
- Instantiated `NotificationController` in `js/ui/applicationBootstrap.js`.
- Refactored `js/app.js` to delegate notification calls to the controller.
- Added unit tests for `NotificationController`.
- Followed AGENTS.md refactoring checklist.
Co-authored-by: PR0M3TH3AN <[email protected]>