refactor(core): asset pipeline overhaul & dock removal

- Introduced IAsset interface and refactored asset loading/saving.
- Migrated TextureContentHeader to Ghost.Engine; updated usage.
- Rewrote AssetRegistry, AssetCatalog, ImportCoordinator for new asset flow.
- Added thread-safe ConcurrentHashSet utility.
- Improved EditorApplication folder management/init.
- Updated TextureAssetHandler/TextureProcessor for new import/export.
- Added EditorContentProvider for asset access.
- Updated AssetManager to use new AssetType enum; removed GCHandle.
- Removed all custom docking controls and templates.
- Deleted obsolete ViewModels/Pages (Console, Hierarchy, Inspector, Project).
- Renamed ProjectBrowser to ContentBrowser; updated references.
- Updated NuGet packages, Result conversions, and commit instructions.
- General cleanup: namespaces, dead code, structure.

src/Editor/Ghost.Editor/Views/Controls/ContentBrowser.xaml.cs

@@ -0,0 +1,147 @@
+using CommunityToolkit.WinUI;
+using Ghost.Editor.Core.Contracts;
+using Ghost.Editor.Models;
+using Ghost.Editor.ViewModels.Controls;
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
+using Microsoft.UI.Xaml.Input;
+
+namespace Ghost.Editor.Views.Controls;
+
+internal sealed partial class ContentBrowser : UserControl
+{
+    public static ContentBrowser? LastFocused
+    {
+        get;
+        private set;
+    }
+
+    private readonly IInspectorService _inspectorService;
+    private bool _isUpdatingSelection = false;
+
+    public ProjectBrowserViewModel ViewModel
+    {
+        get;
+    }
+
+    public ContentBrowser()
+    {
+        _inspectorService = App.GetService<IInspectorService>();
+        ViewModel = App.GetService<ProjectBrowserViewModel>();
+
+        InitializeComponent();
+
+        Loaded += ProjectBrowser_Loaded;
+        Unloaded += ProjectBrowser_Unloaded;
+
+        GettingFocus += ProjectBrowser_GettingFocus;
+    }
+
+    private void ProjectBrowser_GettingFocus(UIElement sender, GettingFocusEventArgs args)
+    {
+        if (_isUpdatingSelection)
+        {
+            return;
+        }
+
+        LastFocused = this;
+    }
+
+    private void ProjectBrowser_Loaded(object sender, RoutedEventArgs e)
+    {
+        _inspectorService.OnSelectionChanged += _inspectorService_OnSelectionChanged;
+    }
+
+    private void ProjectBrowser_Unloaded(object sender, RoutedEventArgs e)
+    {
+        _inspectorService.OnSelectionChanged -= _inspectorService_OnSelectionChanged;
+
+        if (LastFocused == this)
+        {
+            LastFocused = null;
+        }
+    }
+
+    private void _inspectorService_OnSelectionChanged(object? sender, InspectorSelectionChangedEventArgs e)
+    {
+        if (e.Source is not ProjectBrowserViewModel)
+        {
+            PART_FilesView.DeselectAll();
+            PART_DirectoriesView.SelectedNodes.Clear();
+        }
+    }
+
+    private void PART_DirectoriesView_SelectionChanged(TreeView sender, TreeViewSelectionChangedEventArgs args)
+    {
+        if (_isUpdatingSelection)
+        {
+            return;
+        }
+
+        _isUpdatingSelection = true;
+
+        PART_FilesView.DeselectAll();
+        if (args.AddedItems.Count > 0 && args.AddedItems[0] is ExplorerItem selectedItem)
+        {
+            ViewModel.SelectedItem = selectedItem;
+            ViewModel.NavigateToDirectory(selectedItem.FullName);
+        }
+
+        _isUpdatingSelection = false;
+    }
+
+    private void PART_FilesView_SelectionChanged(object sender, SelectionChangedEventArgs args)
+    {
+        if (_isUpdatingSelection)
+        {
+            return;
+        }
+
+        _isUpdatingSelection = true;
+
+        PART_DirectoriesView.SelectedNodes.Clear();
+        if (PART_FilesView.SelectedItem is ExplorerItem selectedItem)
+        {
+            ViewModel.SelectedItem = selectedItem;
+        }
+
+        _isUpdatingSelection = false;
+    }
+
+    private async void PART_FilesView_DoubleTapped(object sender, DoubleTappedRoutedEventArgs e)
+    {
+        if (PART_FilesView.SelectedItem is ExplorerItem selectedItem)
+        {
+            _isUpdatingSelection = true;
+
+            PART_FilesView.DeselectAll();
+            PART_DirectoriesView.SelectedNodes.Clear();
+
+            // NOTE: There is bug that the hover state of the item may remain when navigating to another folder.
+            // Which causes incorrect selection (double click a folder -> directories view select target folder -> files view select the item that has the same index as the double clicked one and the hover visual stay remain from last level)
+            // Not sure if this is a WinUI bug or something else. This may because of the virtualization of the ItemsView.
+            // The core issue is not sure why PART_FilesView_SelectionChanged been triggered after NavigateToDirectory is already finished. And this only happens after the first double click navigation (first time is always fine).
+
+            // HACK: Wait a moment to let the ui clear it's state, otherwise the bug above will happen because of the virtualization.
+            await Task.Delay(100);
+
+            ViewModel.SelectedItem = selectedItem;
+
+            var navigatedItem = ViewModel.OpenSelected();
+            if (navigatedItem.Item1 != null)
+            {
+                if (navigatedItem.Item2 == 0)
+                {
+                    PART_DirectoriesView.SelectedItem = navigatedItem.Item1;
+                }
+                else if (navigatedItem.Item2 == 1)
+                {
+                    var index = ViewModel.Files.IndexOf(navigatedItem.Item1);
+                    PART_FilesView.SelectedIndex = index;
+                }
+            }
+
+            _isUpdatingSelection = false;
+        }
+    }
+}