feat(ui): clear focus from textboxes on Escape in the main window

Mirrors the existing click-outside behavior. Scoped to MainWindow only
(not a generic TopLevel handler) so modal Escape-to-close bindings and
Mission Control's ConPTY tiles are unaffected.

src/ClaudeDo.Ui/Services/FocusClearing.cs

@@ -3,12 +3,16 @@ using Avalonia.Controls;
 using Avalonia.Input;
 using Avalonia.Interactivity;
 using Avalonia.VisualTree;
+using ClaudeDo.Ui.Views;
 
 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.
+/// Escape does the same, but only in the main window: modal windows bind Escape to closing
+/// themselves, and Mission Control's ConPTY tiles need Escape to reach the terminal, so this
+/// intentionally does not use a generic TopLevel handler.
 /// </summary>
 public static class FocusClearing
 {
@@ -16,6 +20,9 @@ public static class FocusClearing
     {
         InputElement.PointerPressedEvent.AddClassHandler<TopLevel>(
             OnPointerPressed, RoutingStrategies.Tunnel, handledEventsToo: true);
+
+        InputElement.KeyDownEvent.AddClassHandler<MainWindow>(
+            OnKeyDown, RoutingStrategies.Tunnel);
     }
 
     private static void OnPointerPressed(TopLevel topLevel, PointerPressedEventArgs e)
@@ -31,4 +38,19 @@ public static class FocusClearing
 
         focusManager.Focus(null);
     }
+
+    private static void OnKeyDown(MainWindow window, KeyEventArgs e)
+    {
+        if (e.Key != Key.Escape)
+            return;
+
+        if (window.FocusManager is not { } focusManager)
+            return;
+
+        if (focusManager.GetFocusedElement() is not TextBox)
+            return;
+
+        focusManager.Focus(null);
+        e.Handled = true;
+    }
 }