fix(agent): cast evidence health for durable gate

apps/api/src/jobs/awooop_ansible_candidate_backfill_job.py

@@ -193,7 +193,9 @@ async def verify_ansible_candidate_pre_decision_evidence(
                       AND NULLIF(recent_logs, '') IS NOT NULL
                       AND EXISTS (
                           SELECT 1
-                          FROM jsonb_each(coalesce(mcp_health, '{}'::jsonb)) health
+                          FROM jsonb_each(
+                              coalesce(CAST(mcp_health AS jsonb), '{}'::jsonb)
+                          ) health
                           WHERE health.value = 'true'::jsonb
                       )
                 )