chore: snapshot workflow migration progress

backend/app/domains/notifications/service.py

@@ -5,7 +5,7 @@ to create notification rows in the audit_log table.
 """
 import logging
 import uuid
-from datetime import datetime
+from datetime import datetime, timezone
 
 from sqlalchemy import create_engine, select
 from sqlalchemy.orm import Session
@@ -23,6 +23,11 @@ CHANNEL_ALERT = "alert"              # admin-only infrastructure issues
 _engine = None
 
 
+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)
+
+
 def _get_engine():
     global _engine
     if _engine is None:
@@ -53,7 +58,7 @@ async def emit_notification(
             details=details,
             notification=True,
             channel=channel,
-            timestamp=datetime.utcnow(),
+            timestamp=_utcnow_naive(),
         )
         db.add(entry)
         await db.commit()
@@ -85,7 +90,7 @@ def emit_notification_sync(
                 details=details,
                 notification=True,
                 channel=channel,
-                timestamp=datetime.utcnow(),
+                timestamp=_utcnow_naive(),
             )
             session.add(entry)
             session.commit()
@@ -149,7 +154,7 @@ def emit_batch_render_notification_sync(order_id: str) -> None:
                 },
                 notification=True,
                 channel=CHANNEL_NOTIFICATION,
-                timestamp=datetime.utcnow(),
+                timestamp=_utcnow_naive(),
             )
             session.add(entry)
             session.commit()