Improve desktop UX and accessibility

LehrerApp.Desktop/Views/MainWindow.axaml.cs

@@ -36,6 +36,13 @@ public partial class MainWindow : Window
             return;
         }
 
+        if (commandModifier && TryGetNavigationShortcut(e.Key, out var destination))
+        {
+            vm.NavigateToCommand.Execute(destination);
+            e.Handled = true;
+            return;
+        }
+
         if (!vm.IsCommandPaletteOpen) return;
         if (e.Key == Key.Escape)
         {
@@ -54,6 +61,23 @@ public partial class MainWindow : Window
         }
     }
 
+    private static bool TryGetNavigationShortcut(Key key, out NavItem destination)
+    {
+        destination = key switch
+        {
+            Key.D1 or Key.NumPad1 => NavItem.Dashboard,
+            Key.D2 or Key.NumPad2 => NavItem.Groups,
+            Key.D3 or Key.NumPad3 => NavItem.Students,
+            Key.D4 or Key.NumPad4 => NavItem.Exams,
+            Key.D5 or Key.NumPad5 => NavItem.Planner,
+            Key.D6 or Key.NumPad6 => NavItem.Workload,
+            Key.D7 or Key.NumPad7 => NavItem.ClassTeacher,
+            Key.D8 or Key.NumPad8 => NavItem.Settings,
+            _ => default,
+        };
+        return key is >= Key.D1 and <= Key.D8 or >= Key.NumPad1 and <= Key.NumPad8;
+    }
+
     private void OnOpenCommandPaletteClick(object? sender, Avalonia.Interactivity.RoutedEventArgs e)
     {
         if (DataContext is MainWindowViewModel vm)