feat(ui): clear textbox focus on click outside any text box

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/ClaudeDo.App/App.axaml.cs

@@ -21,6 +21,8 @@ public partial class App : Application
     {
         if (ApplicationLifetime is IClassicDesktopStyleApplicationLifetime desktop)
         {
+            FocusClearing.Install();
+
             desktop.MainWindow = new MainWindow
             {
                 DataContext = Services.GetRequiredService<IslandsShellViewModel>(),

src/ClaudeDo.Ui/Services/FocusClearing.cs

@@ -0,0 +1,34 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Input;
+using Avalonia.Interactivity;
+using Avalonia.VisualTree;
+
+namespace ClaudeDo.Ui.Services;
+
+/// <summary>
+/// Clears focus from a TextBox when the user clicks outside of any text box, so input
+/// fields behave like the user expects. Registered once for every window in the app.
+/// </summary>
+public static class FocusClearing
+{
+    public static void Install()
+    {
+        InputElement.PointerPressedEvent.AddClassHandler<TopLevel>(
+            OnPointerPressed, RoutingStrategies.Tunnel, handledEventsToo: true);
+    }
+
+    private static void OnPointerPressed(TopLevel topLevel, PointerPressedEventArgs e)
+    {
+        if (topLevel.FocusManager is not { } focusManager)
+            return;
+
+        if (focusManager.GetFocusedElement() is not TextBox)
+            return;
+
+        if (e.Source is Visual v && v.FindAncestorOfType<TextBox>(includeSelf: true) is not null)
+            return;
+
+        focusManager.Focus(null);
+    }
+}