feat(dock): implement tab tear-off to new window

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

@@ -290,10 +290,27 @@ public sealed partial class DockLayout : Control
         tabView.DragLeave += TabView_DragLeave;
         tabView.Drop += TabView_Drop;
         tabView.TabDragStarting += TabView_TabDragStarting;
+        tabView.TabDroppedOutside += TabView_TabDroppedOutside;
 
         return tabView;
     }
 
+    private void TabView_TabDroppedOutside(Microsoft.UI.Xaml.Controls.TabView sender, Microsoft.UI.Xaml.Controls.TabViewTabDroppedOutsideEventArgs args)
+    {
+        if (_sourceNode != null && _draggedItem != null)
+        {
+            // Remove from current tree
+            _sourceNode.Items.Remove(_draggedItem);
+            DockMutationEngine.CleanupEmptyNodes(_sourceNode, Root);
+
+            // Create new window
+            var newWindow = new Ghost.Editor.View.Windows.DockWindow(_draggedItem);
+            newWindow.Activate();
+
+            ClearDragOperationState();
+        }
+    }
+
     private object? _draggedItem;
     private DockPanelNode? _sourceNode;
     private DockPosition _currentDropPosition = DockPosition.None;

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

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<winex:WindowEx
+    x:Class="Ghost.Editor.View.Windows.DockWindow"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:controls="using:Ghost.Editor.View.Controls"
+    xmlns:winex="using:WinUIEx">
+    <Grid>
+        <controls:DockLayout x:Name="PART_DockLayout" />
+    </Grid>
+</winex:WindowEx>

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

@@ -0,0 +1,22 @@
+using Ghost.Editor.Core.Controls.Internal.Docking;
+using WinUIEx;
+
+namespace Ghost.Editor.View.Windows;
+
+public sealed partial class DockWindow : WindowEx
+{
+    public DockWindow(object initialTabContent)
+    {
+        InitializeComponent();
+        
+        // Setup initial single panel layout
+        var rootGroup = new DockGroupNode();
+        var panel = new DockPanelNode();
+        panel.Items.Add(initialTabContent);
+        rootGroup.AddChild(panel);
+        
+        PART_DockLayout.Root = rootGroup;
+        
+        // Optional: Titlebar setup etc.
+    }
+}