feat(asset): modern asset system with SQLite catalog

Refactored asset management to use a persistent, thread-safe SQLite-backed AssetCatalog, replacing in-memory dictionaries.
Added AssetHandlerRegistry for O(1) handler lookup, ImportCoordinator for async background importing, and robust AssetMeta/AssetMetaIO for JSON-based metadata and settings.
Refactored AssetRegistry to integrate these components and support auto-import via file system watcher.
Updated IImportableAssetHandler for handler-specific settings and polymorphic serialization.
Added comprehensive unit tests for all new systems.
Removed obsolete code and legacy integration tests.

BREAKING CHANGE: Asset system APIs and storage format have changed; migration required for existing projects.

src/Editor/Ghost.Editor.Core/Attributes.cs

@@ -55,23 +55,10 @@ public class EditorInjectionAttribute : DiscoverableAttributeBase
     {
         Singleton,
         Transient,
-        Scoped
     }
 
-    public ServiceLifetime Lifetime
+    public EditorInjectionAttribute(ServiceLifetime lifetime, Type implementationType)
     {
-        get;
-    }
-
-    public Type? ImplementationType
-    {
-        get;
-    }
-
-    public EditorInjectionAttribute(ServiceLifetime lifetime, Type? implementationType = null)
-    {
-        Lifetime = lifetime;
-        ImplementationType = implementationType;
     }
 }