fix(governance): cast dispatch status filter

apps/api/src/services/governance_query_service.py

@@ -275,14 +275,14 @@ async def _query_dispatch_table(
             NULL::text AS operator_note
         FROM governance_remediation_dispatch d
         JOIN ai_governance_events e ON e.id = d.governance_event_id
-        WHERE d.dispatch_status = :dispatch_status
+        WHERE d.dispatch_status = CAST(:dispatch_status AS governance_dispatch_status)
         ORDER BY d.dispatched_at DESC
     """)
 
     count_sql = text("""
         SELECT count(*) AS cnt
         FROM governance_remediation_dispatch
-        WHERE dispatch_status = :dispatch_status
+        WHERE dispatch_status = CAST(:dispatch_status AS governance_dispatch_status)
     """)
 
     async with get_db_context() as db: