Arn Infra Cleanup

- This skill should be used when the user says "cleanup", "infra cleanup", "arn infra cleanup", "clean up resources", "destroy expired resources", "check ttl", "check expired", "ttl cleanup", "remove old deployments", "destroy dev environment", "tear down", "teardown infra", "destroy resources", "cleanup ephemeral", "check for expired resources", "clean up infra", "resource cleanup", "destroy old resources", "prune resources", "delete expired deployments", "decommission", or wants to check for and destroy expired ephemeral infrastructure resources. This skill also supports periodic monitoring via /loop 6h /arn-infra-cleanup for session-duration TTL enforcement.