Baseline: WPF/Avalonia/Cli/Core + plans (BROWSER_FEATURES_PLAN v2, MOBILE_PLAN v1)

VideoDownloader.Avalonia/MainWindow.axaml.cs

@@ -0,0 +1,19 @@
+using Avalonia.Controls;
+
+namespace VideoDownloader.Avalonia;
+
+public partial class MainWindow : Window
+{
+    public MainWindow()
+    {
+        InitializeComponent();
+        DataContext = new MainViewModel();
+        // URL 입력창에 포커스 + Enter 로 받기 실행.
+        UrlBox.AttachedToVisualTree += (_, _) => UrlBox.Focus();
+        UrlBox.KeyDown += (_, e) =>
+        {
+            if (e.Key == global::Avalonia.Input.Key.Enter && DataContext is MainViewModel vm && !vm.IsBusy && !string.IsNullOrWhiteSpace(vm.Url))
+                vm.DownloadCommand.Execute(null);
+        };
+    }
+}