feat(app_assets): enhance asset management with CachedPresignStorage

- Introduced CachedPresignStorage to cache presigned download URLs, reducing repeated API calls.
- Updated AppAssetService to utilize CachedPresignStorage for improved performance in asset download URL generation.
- Refactored asset builders and packagers to support the new storage mechanism.
- Removed unused AppAssetsAttrsInitializer to streamline initialization processes.
- Added unit tests for CachedPresignStorage to ensure functionality and reliability.

api/core/app_assets/builder/pipeline.py

@@ -1,6 +1,4 @@
 from core.app.entities.app_asset_entities import AppAssetFileTree
-from core.app_assets.builder.file_builder import FileBuilder
-from core.app_assets.builder.skill_builder import SkillBuilder
 from core.app_assets.entities import AssetItem
 
 from .base import AssetBuilder, BuildContext
@@ -9,8 +7,8 @@ from .base import AssetBuilder, BuildContext
 class AssetBuildPipeline:
     _builders: list[AssetBuilder]
 
-    def __init__(self, builders: list[AssetBuilder] | None = None) -> None:
-        self._builders = builders or [SkillBuilder(), FileBuilder()]
+    def __init__(self, builders: list[AssetBuilder]) -> None:
+        self._builders = builders
 
     def build_all(self, tree: AppAssetFileTree, ctx: BuildContext) -> list[AssetItem]:
         # 1. Distribute: each node goes to first accepting builder