feat: initial project structure with Snake.Core, CLI and Avalonia skeleton

Snake.Avalonia/Views/GameView.axaml.cs

@@ -0,0 +1,15 @@
+using Avalonia.Controls;
+
+namespace Snake.Avalonia.Views;
+
+/// <summary>
+/// Placeholder for the Avalonia game view.
+/// Wire up <see cref="Snake.Core.SnakeGame"/> here for rendering and input.
+/// </summary>
+public partial class GameView : UserControl
+{
+    public GameView()
+    {
+        InitializeComponent();
+    }
+}