- stop using multiple background task, the appCoordinator sync one is enough for the whole app
- move the AppMeditor to the MainActor
- expose the WindowManager through the AppMediator
- hide sensitive WindowManager API behind a different protocol
- remove the now unnecessary `BackgroundTaskService`
- combine multiple services to handle app wide requests
- remove direct UIApplication access from everywhere
- fix#2703 by combining UIApplication.applicationState with the WindowManager's main window appearance
- leave the door open for more app control in the future (especiall for the mac)