refactor: Storage 改用工厂模式，server reload 接入 uvicorn

- 新增 StorageFactory(BaseFactory[BaseStorage]) 替代手写 dict 注册
- H5Storage / JSONStorage 通过 @StorageFactory.register 注册
- dataset.py 使用 StorageFactory.create() 替代 create_storage()
- 删除 create_storage / available_storage_types 死函数
- server.py reload 参数正式传入 uvicorn.run()

astrai/dataset/__init__.py

@@ -9,8 +9,7 @@ from astrai.dataset.storage import (
     H5Storage,
     JSONStorage,
     MultiSegmentFetcher,
-    available_storage_types,
-    create_storage,
+    StorageFactory,
     detect_format,
     load_h5,
     load_json,
@@ -26,9 +25,8 @@ __all__ = [
     "BaseStorage",
     "H5Storage",
     "JSONStorage",
-    "create_storage",
+    "StorageFactory",
     "detect_format",
-    "available_storage_types",
     "save_h5",
     "load_h5",
     "save_json",