Add datasource quality and schema gates

src/govoplan_datasources/backend/router.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+from collections.abc import Mapping
+
 from fastapi import APIRouter, Depends, HTTPException, Query, status
 from sqlalchemy.orm import Session
 
@@ -224,6 +226,11 @@ def api_create_stage(
             "mode": stage.mode,
             "row_count": stage.row_count,
             "fingerprint": stage.fingerprint,
+            "validation_valid": stage.validation.get("valid"),
+            "quality_policy_hash": stage.validation.get("policy_hash"),
+            "schema_classification": _safe_mapping(
+                stage.validation.get("schema_change")
+            ).get("classification"),
         },
     )
     session.commit()
@@ -262,6 +269,9 @@ def api_promote_stage(
             "materialization_ref": materialization.ref,
             "revision": materialization.revision,
             "frozen": materialization.frozen_at is not None,
+            "quality_policy_hash": _safe_mapping(
+                materialization.provenance.get("stage_validation")
+            ).get("policy_hash"),
         },
     )
     session.commit()
@@ -663,6 +673,10 @@ def _governance(
     return DatasourceGovernance.from_mapping(payload.model_dump())
 
 
+def _safe_mapping(value: object) -> Mapping[str, object]:
+    return value if isinstance(value, Mapping) else {}
+
+
 def _audit(
     session: Session,
     principal: ApiPrincipal,