feat: WIP: add template.

demo/Ursa.Demo/ViewModels/PaginationDemoViewModel.cs

@@ -0,0 +1,10 @@
+using System.Collections.ObjectModel;
+using Avalonia.Collections;
+using CommunityToolkit.Mvvm.ComponentModel;
+
+namespace Ursa.Demo.ViewModels;
+
+public class PaginationDemoViewModel: ObservableObject
+{
+    public AvaloniaList<int> PageSizes { get; set; } = new() { 10, 20, 50, 100 };
+}