feat: Implement Playlists and Programs Management

- Added PlaylistsGroupViewModel to manage playlists and selection.
- Introduced ProgramsGroupViewModel for handling program groups and subscriptions.
- Created ProgramsListViewModel to manage individual program listings.
- Developed SettingsViewModel for user settings including playlist management.
- Implemented TVPlayerViewModel as the main view model coordinating screens and data.
- Added PlayerView for video playback with LibVLC integration.
- Created XAML views for PlaylistsGroup, ProgramsGroup, ProgramsList, and Settings.
- Added sample M3U playlist for testing.
- Documented WPF build instructions and project structure in WPF-BUILD.md.
- Configured global.json for .NET SDK versioning.

TV Player Avalonia/App.axaml

@@ -0,0 +1,28 @@
+<Application xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:vm="clr-namespace:TV_Player.AvaloniaApp.ViewModels"
+             xmlns:views="clr-namespace:TV_Player.AvaloniaApp.Views"
+             x:Class="TV_Player.AvaloniaApp.App"
+             RequestedThemeVariant="Dark">
+  <Application.Styles>
+    <FluentTheme />
+  </Application.Styles>
+
+  <Application.DataTemplates>
+    <DataTemplate DataType="vm:PlaylistsGroupViewModel">
+      <views:PlaylistsGroupView />
+    </DataTemplate>
+    <DataTemplate DataType="vm:ProgramsGroupViewModel">
+      <views:ProgramsGroupView />
+    </DataTemplate>
+    <DataTemplate DataType="vm:ProgramsListViewModel">
+      <views:ProgramsListView />
+    </DataTemplate>
+    <DataTemplate DataType="vm:PlayerViewModel">
+      <views:PlayerView />
+    </DataTemplate>
+    <DataTemplate DataType="vm:SettingsViewModel">
+      <views:SettingsView />
+    </DataTemplate>
+  </Application.DataTemplates>
+</Application>