feat: introduce attribute management system for sandbox

- Added AttrMap and AttrKey classes for type-safe attribute storage.
- Implemented AppAssetsAttrs and SkillAttrs for managing application and skill attributes.
- Refactored Sandbox and initializers to utilize the new attribute management system, enhancing modularity and clarity in asset handling.

api/services/app_asset_service.py

@@ -58,6 +58,22 @@ class AppAssetService:
             session.commit()
         return assets
 
+    @staticmethod
+    def get_tenant_app_assets(tenant_id: str, assets_id: str) -> AppAssets:
+        with Session(db.engine, expire_on_commit=False) as session:
+            app_assets = (
+                session.query(AppAssets)
+                .filter(
+                    AppAssets.tenant_id == tenant_id,
+                    AppAssets.id == assets_id,
+                )
+                .first()
+            )
+            if not app_assets:
+                raise ValueError(f"App assets not found for tenant_id={tenant_id}, assets_id={assets_id}")
+
+            return app_assets
+
     @staticmethod
     def get_assets(tenant_id: str, app_id: str, user_id: str, *, is_draft: bool) -> AppAssets | None:
         with Session(db.engine, expire_on_commit=False) as session: