feat(storage): add local storage framework

backend/hermes/app/storage/base.py

@@ -0,0 +1,34 @@
+from abc import ABC, abstractmethod
+from pathlib import Path
+
+from app.storage.schemas import FileMetadata, StoredFileMetadata
+
+
+class StorageProvider(ABC):
+    @abstractmethod
+    def save_file(
+        self,
+        *,
+        namespace: str,
+        content: bytes,
+        original_filename: str,
+        stored_filename: str,
+        mime_type: str,
+    ) -> StoredFileMetadata:
+        raise NotImplementedError
+
+    @abstractmethod
+    def open_file(self, storage_key: str) -> Path:
+        raise NotImplementedError
+
+    @abstractmethod
+    def delete_file(self, storage_key: str) -> None:
+        raise NotImplementedError
+
+    @abstractmethod
+    def file_exists(self, storage_key: str) -> bool:
+        raise NotImplementedError
+
+    @abstractmethod
+    def get_file_metadata(self, storage_key: str) -> FileMetadata:
+        raise NotImplementedError