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/ActivationHandler.cs

@@ -62,7 +62,6 @@ internal static class ActivationHandler
         };
 
         AllocationManager.Initialize(opts);
-        TypeCache.Initialize();
         
         //App.GetService<EngineCore>();