feat(api): 支持 x-api-version (#29)

* feat(relationship): support legacy-compatible response format

* feat(score): add support for legacy score response format in API

* fix(score): avoid missing greenlet

* fix(score): fix missing field for model validation

* feat(user): apply legacy score format for user

* feat(api): use `int` to hint `APIVersion`

app/dependencies/api_version.py

@@ -0,0 +1,16 @@
+from __future__ import annotations
+
+from typing import Annotated
+
+from fastapi import Depends, Header
+
+
+def get_api_version(version: int | None = Header(None, alias="x-api-version")) -> int:
+    if version is None:
+        return 0
+    if version < 1:
+        raise ValueError
+    return version
+
+
+APIVersion = Annotated[int, Depends(get_api_version)]