feat: redesign banner demo.

demo/Ursa.Demo/Pages/BannerDemo.axaml.cs

@@ -1,7 +1,4 @@
 using Avalonia.Controls;
-using Avalonia.Controls.Notifications;
-using Avalonia.Markup.Xaml;
-using CommunityToolkit.Mvvm.ComponentModel;
 using Ursa.Demo.ViewModels;
 
 namespace Ursa.Demo.Pages;
@@ -13,16 +10,4 @@ public partial class BannerDemo : UserControl
         InitializeComponent();
         this.DataContext = new BannerDemoViewModel();
     }
-
-    private void InitializeComponent()
-    {
-        AvaloniaXamlLoader.Load(this);
-    }
-}
-
-public partial class BannerDemoViewModel : ViewModelBase
-{
-    [ObservableProperty] private NotificationType _selectedType;
-    [ObservableProperty] private bool _bordered;
-    [ObservableProperty] private bool _canClose;
 }