Fix: resolve memory leaks and remove debug info leakage

[rm335]

Summary

• Remove debug print(keyCode) in GlobalKeybindingPreferences.description that leaked user hotkey data to the
  system console
• Add removeObserver(self) in LauncherApplication/AppDelegate.applicationWillTerminate —
  DistributedNotificationCenter does not use zeroing-weak references, so unremoved observers risk a crash on dealloc
• Add deinit with removeObserver(self) to PreferencesViewController — observer registered in viewDidLoad had
  no cleanup path
• Use [weak self] in two DispatchQueue.main.asyncAfter closures in StatusBarController to prevent retaining
  self beyond intended lifetime

Test plan

• Verify global hotkey still works after setting it in Preferences
• Open and close Preferences window multiple times, confirm no observer accumulation (use Instruments Allocations)
• Confirm LauncherApplication terminates cleanly without console crash logs
• Confirm auto-collapse timer still fires correctly after expanding the menu bar
• Verify no keyCode output appears in Console.app during normal usage