fix(api): catch DataError in /alerts/query to return 400 instead of 500

When a CEL filter contains a non-UUID value against a UUID-typed column,
PostgreSQL raises a DataError which was not caught — only CelToSqlException
was handled, so FastAPI returned a 500.

Add an explicit except DataError block that returns a 400 with a clear
message. This is a provider-agnostic safety net: any provider that stores
a non-UUID alert id would hit the same crash, regardless of fixes applied
at the provider level.

Related: keephq#6219 (fixes root cause in Prometheus provider).

Author: alihb2026

keep/api/routes/alerts.py

@@ -16,6 +16,7 @@
 from fastapi.responses import JSONResponse
 from pusher import Pusher
 from sqlalchemy_utils import UUIDType
+from sqlalchemy.exc import DataError
 from sqlmodel import Session
 
 from keep.api.arq_pool import get_pool
@@ -228,6 +229,14 @@ def query_alerts(
         raise HTTPException(
             status_code=400, detail=f"Error parsing CEL expression: {query.cel}"
         ) from e
+    except DataError as e:
+        logger.exception(
+            f'Database type error while executing query "{query.cel}". {str(e)}'
+        )
+        raise HTTPException(
+            status_code=400,
+            detail=f"Invalid value in query - a field may contain a non-UUID value: {query.cel}",
+        ) from e
 
     db_alerts = enrich_alerts_with_incidents(tenant_id, db_alerts)
     enriched_alerts_dto = convert_db_alerts_to_dto_alerts(