implemented comprehensive accessibility (A11y) support across the app

lib/view/pages/overhang.dart

@@ -23,6 +23,7 @@ class _OverhangState extends State<Overhang> {
       title: const Text('Mehr'),
       actions: [
         IconButton(
+          tooltip: 'Einstellungen',
           onPressed: () => AppRoutes.openSettings(context),
           icon: const Icon(Icons.settings),
         ),