Refactor project from Ghost.App to Ghost.Editor

Changed the project structure to reflect a shift from `Ghost.App` to `Ghost.Editor`, updating namespaces and class names throughout.

Changed the application class in `App.xaml` and `App.xaml.cs` from `GhostApplication` to `EditorApplication`.

Changed several service interfaces to reside under `Ghost.Editor.Services.Contracts`, including `IInspectorService`, `INotificationService`, and `IProgressService`.

Added `InspectorView` and `InspectorViewModel` classes to manage inspector functionality.

Added `NavigationTabView` and `NavigationTabPage` classes to facilitate navigation within the editor.

Enhanced `WorldNode` and `EntityNode` classes to support scene graph functionality, including serialization and entity management.

Updated the project file `Ghost.Editor.csproj` to reflect the new structure and removed old references.

Modified the solution file `GhostEngine.sln` to remove references to `Ghost.App` and include `Ghost.Editor`.

Updated unit tests to align with the new namespaces and project structure.

Ghost.App/ViewModels/Pages/EngineEditor/InspectorViewModel.cs

@@ -0,0 +1,32 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using Ghost.Editor.Contracts;
+using Ghost.Editor.Services.Contracts;
+
+namespace Ghost.Editor.ViewModels.Pages.EngineEditor;
+
+internal partial class InspectorViewModel(IInspectorService inspectorService) : ObservableObject, INavigationAware
+{
+    [ObservableProperty]
+    public partial IInspectable? Inspectable
+    {
+        get;
+        set;
+    }
+
+    public void OnNavigatedTo(object? parameter)
+    {
+        inspectorService.OnSelectionChanged += OnSelectionChanged;
+        Inspectable = inspectorService.SelectedInspectable;
+    }
+
+    public void OnNavigatedFrom()
+    {
+        inspectorService.OnSelectionChanged -= OnSelectionChanged;
+        Inspectable = null;
+    }
+
+    private void OnSelectionChanged()
+    {
+        Inspectable = inspectorService.SelectedInspectable;
+    }
+}