chore: snapshot workflow migration progress

backend/app/domains/orders/service.py

@@ -1,5 +1,5 @@
 """Order service — order number generation and business logic."""
-from datetime import datetime
+from datetime import datetime, timezone
 from sqlalchemy.ext.asyncio import AsyncSession
 from sqlalchemy import select, func, create_engine, update as sql_update
 from sqlalchemy.orm import Session
@@ -9,9 +9,14 @@ import logging
 logger = logging.getLogger(__name__)
 
 
+def _utcnow_naive() -> datetime:
+    """Return UTC as a naive datetime for legacy TIMESTAMP WITHOUT TIME ZONE columns."""
+    return datetime.now(timezone.utc).replace(tzinfo=None)
+
+
 async def generate_order_number(db: AsyncSession) -> str:
     """Generate next sequential order number: SA-2026-XXXXX."""
-    year = datetime.utcnow().year
+    year = datetime.now(timezone.utc).year
     prefix = f"SA-{year}-"
 
     # Use MAX to find the highest existing sequence number this year.
@@ -68,7 +73,7 @@ def check_order_completion(order_id: str) -> bool:
                 return False
 
             # Auto-advance to completed
-            now = datetime.utcnow()
+            now = _utcnow_naive()
             session.execute(
                 sql_update(Order)
                 .where(Order.id == order_id)