feat(ui): list reordering, quick actions, and resizable modals

- Drag-to-reorder user lists in the sidebar, persisted via a new
  list sort_order column (AddListSortOrder migration, backfilled by
  creation time) and ListRepository.ReorderAsync
- "Open in Explorer" / "Open in Terminal" context-menu actions on lists
- "Clear all completed" button on the Tasks island
- Inline-edit subtask titles (empty text deletes the step) and
  click-to-copy task ID in the Details island
- Make modal and planning windows resizable (BorderOnly decorations
  with min sizes) instead of fixed-size borderless

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/ClaudeDo.Ui/Views/Islands/DetailsIslandView.axaml.cs

@@ -1,9 +1,13 @@
+using System.Linq;
 using Avalonia;
 using Avalonia.Controls;
+using Avalonia.Input;
 using Avalonia.Input.Platform;
 using Avalonia.Interactivity;
 using Avalonia.Layout;
 using Avalonia.Media;
+using Avalonia.Threading;
+using Avalonia.VisualTree;
 using ClaudeDo.Ui.ViewModels.Islands;
 using ClaudeDo.Ui.Views.Modals;
 using ClaudeDo.Ui.Views.Planning;
@@ -135,6 +139,31 @@ public partial class DetailsIslandView : UserControl
         return await tcs.Task;
     }
 
+    private void OnSubtaskTitleTapped(object? sender, TappedEventArgs e)
+    {
+        if (sender is not Control c || c.DataContext is not SubtaskRowViewModel row) return;
+        row.IsEditing = true;
+
+        var box = (c.GetVisualParent() as Panel)?.GetVisualDescendants().OfType<TextBox>().FirstOrDefault();
+        if (box is not null)
+            Dispatcher.UIThread.Post(() => { box.Focus(); box.SelectAll(); }, DispatcherPriority.Background);
+    }
+
+    private void OnSubtaskEditLostFocus(object? sender, RoutedEventArgs e)
+    {
+        if (DataContext is DetailsIslandViewModel vm
+            && sender is Control c && c.DataContext is SubtaskRowViewModel row)
+            vm.CommitSubtaskEditCommand.Execute(row);
+    }
+
+    private async void OnTaskIdTapped(object? sender, TappedEventArgs e)
+    {
+        if (DataContext is not DetailsIslandViewModel vm || vm.Task is null) return;
+        var clipboard = TopLevel.GetTopLevel(this)?.Clipboard;
+        if (clipboard is null) return;
+        await clipboard.SetTextAsync(vm.Task.Id);
+    }
+
     private async void OnCopyDescriptionClick(object? sender, RoutedEventArgs e)
     {
         if (DataContext is not DetailsIslandViewModel vm) return;