fix: move from __future__ import annotations to top of payments.py

Python requires from __future__ imports to be at the beginning of the file.
The import was at line 10, causing SyntaxError during coordinator-api startup.

apps/coordinator-api/src/app/services/payments.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 from typing import Annotated
 
 from fastapi import Depends
@@ -7,8 +9,6 @@ from sqlalchemy.orm import Session
 
 from datetime import datetime, timedelta
 
-from __future__ import annotations
-
 from aitbc import get_logger, AITBCHTTPClient, NetworkError
 logger = get_logger(__name__)