feat: implement OAuth2 login

backend/src/auth/router.py

@@ -0,0 +1,33 @@
+from fastapi import APIRouter, Depends
+from fastapi import status
+from sqlalchemy import select
+
+from auth.config import OAuth2Config
+from auth.db import User
+from auth.schemas import UserRead
+from auth.users import current_superuser
+from database import DbSessionDependency
+from auth.users import oauth_client
+
+users_router = APIRouter()
+auth_metadata_router = APIRouter()
+oauth_enabled = oauth_client is not None
+if oauth_enabled:
+    oauth_config = OAuth2Config()
+
+
+@users_router.get("/users/all", status_code=status.HTTP_200_OK, dependencies=[Depends(current_superuser)])
+def get_all_users(db: DbSessionDependency) -> list[UserRead]:
+    stmt = select(User)
+    result = db.execute(stmt).scalars().unique()
+    return [UserRead.model_validate(user) for user in result]
+
+
+@auth_metadata_router.get("/auth/metadata", status_code=status.HTTP_200_OK)
+def get_auth_metadata() -> dict:
+    if oauth_enabled:
+        return {
+            "oauth_name": oauth_config.name,
+        }
+    else:
+        return {"oauth_name": None}