Adds a checkable MenuItem so the user can opt out of the hide-to-tray
behavior. Persisted per-user to %APPDATA%\WebhookServer\gui.json so the
choice survives restarts.
When ticked (default): X / Alt+F4 / minimize hide to tray, GUI process
keeps running, tray icon persists.
When unticked: X actually closes the app, minimize is a regular
Windows minimize.
Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>