WindowKiller 2025.07.30.3

Refactor app logic and improve UX

- Updated GitHub release workflow to include repo name in tag.
- Changed form title to "Window Killer" in `Form1.Designer.cs`.
- Reformatted confirmation dialog for better readability.
- Added mutex to enforce single instance of the app.
- Refactored notification bar icon setup into `SetupNotificationBarIcon`.
  - Added context menu with "Quit" option and title label.
- Updated README with instructions for exiting the app.
- Performed general code cleanup for better maintainability.