feat: add demo for presenter temporarily.

demo/Ursa.Demo/Pages/TimePickerDemo.axaml

@@ -0,0 +1,11 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             xmlns:u="https://irihi.tech/ursa"
+             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
+             x:Class="Ursa.Demo.Pages.TimePickerDemo">
+    <StackPanel HorizontalAlignment="Left">
+        <u:TimePickerPresenter HorizontalAlignment="Left" VerticalAlignment="Top"/>
+    </StackPanel>
+</UserControl>

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

@@ -0,0 +1,13 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+
+namespace Ursa.Demo.Pages;
+
+public partial class TimePickerDemo : UserControl
+{
+    public TimePickerDemo()
+    {
+        InitializeComponent();
+    }
+}

demo/Ursa.Demo/ViewModels/MainViewViewModel.cs

@@ -55,6 +55,7 @@ public class MainViewViewModel : ViewModelBase
             MenuKeys.MenuKeySelectionList => new SelectionListDemoViewModel(),
             MenuKeys.MenuKeySkeleton => new SkeletonDemoViewModel(),
             MenuKeys.MenuKeyTagInput => new TagInputDemoViewModel(),
+            MenuKeys.MenuKeyTimePicker => new TimePickerDemoViewModel(),
             MenuKeys.MenuKeyTimeline => new TimelineDemoViewModel(),
             MenuKeys.MenuKeyTreeComboBox => new TreeComboBoxDemoViewModel(),
             MenuKeys.MenuKeyTwoTonePathIcon => new TwoTonePathIconDemoViewModel(),

demo/Ursa.Demo/ViewModels/MenuViewModel.cs

@@ -43,6 +43,7 @@ public class MenuViewModel: ViewModelBase
             new() { MenuHeader = "Skeleton", Key = MenuKeys.MenuKeySkeleton },
             new() { MenuHeader = "TagInput", Key = MenuKeys.MenuKeyTagInput },
             new() { MenuHeader = "Theme Toggler", Key = MenuKeys.MenuKeyThemeToggler },
+            new() { MenuHeader = "TimePicker", Key = MenuKeys.MenuKeyTimePicker },
             new() { MenuHeader = "Timeline", Key = MenuKeys.MenuKeyTimeline },
             new() { MenuHeader = "TreeComboBox", Key = MenuKeys.MenuKeyTreeComboBox },
             new() { MenuHeader = "TwoTonePathIcon", Key = MenuKeys.MenuKeyTwoTonePathIcon},
@@ -86,6 +87,7 @@ public static class MenuKeys
     public const string MenuKeySelectionList = "SelectionList";
     public const string MenuKeyTagInput = "TagInput";
     public const string MenuKeySkeleton = "Skeleton"; 
+    public const string MenuKeyTimePicker = "TimePicker";
     public const string MenuKeyTimeline = "Timeline";
     public const string MenuKeyTwoTonePathIcon = "TwoTonePathIcon";
     public const string MenuKeyThemeToggler = "ThemeToggler";

demo/Ursa.Demo/ViewModels/TimePickerDemoViewModel.cs

@@ -0,0 +1,8 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+
+namespace Ursa.Demo.ViewModels;
+
+public class TimePickerDemoViewModel: ObservableObject
+{
+    
+}