fix(dock): complete TabTearOffService migration and restore transactional integrity

src/Editor/Ghost.Editor.Core/Controls/Internal/Docking/TabTearOffService.cs

@@ -72,7 +72,6 @@ internal static class TabTearOffService
 
     private static void RestoreSelection(object? container, object? selection)
     {
-        if (selection == null) return;
         if (container is DockPanelNode panel) panel.SelectedItem = selection;
         else if (container is TabView tabView) tabView.SelectedItem = selection;
     }

src/Editor/Ghost.Editor/View/Controls/DockLayout.cs

@@ -436,8 +436,13 @@ public sealed partial class DockLayout : Control
                 {
                     var result = TabTearOffService.TryTearOffTab(sourceNode.Items, args.Item, (tab) =>
                     {
+                        if (TabTornOff == null)
+                        {
+                            throw new InvalidOperationException("No tear-off handler attached.");
+                        }
+
                         // Raise event to let the host handle window creation
-                        TabTornOff?.Invoke(this, new TabTornOffEventArgs(tab, sourceNode));
+                        TabTornOff.Invoke(this, new TabTornOffEventArgs(tab, sourceNode));
                     }, sourceNode);
 
                     if (result.IsSuccess)

src/Editor/Ghost.Editor/View/Windows/DockWindow.xaml.cs

@@ -22,16 +22,7 @@ internal sealed partial class DockWindow : WindowEx
     }
 
     private void OnTabTornOff(object? sender, TabTornOffEventArgs e)
-    {
-        try
     {
         App.CreateAndShowDockWindow(e.TabContent);
     }
-        catch (Exception ex)
-        {
-            Logger.LogError(ex);
-            // The service handles rollback if this was called from TryTearOffTab
-            throw; 
-        }
-    }
 }

src/Editor/Ghost.Editor/View/Windows/EngineEditorWindow.xaml.cs

@@ -2,6 +2,7 @@ using Ghost.Core;
 using Ghost.Editor.Core;
 using Ghost.Editor.Core.Contracts;
 using Ghost.Editor.Core.Services;
+using Ghost.Editor.Core.Controls.Internal.Docking;
 using Ghost.Editor.View.Controls;
 using Ghost.Editor.ViewModels.Windows;
 using Windows.ApplicationModel;