mirrord 3.254.0 stops a failed iptables teardown from disconnecting every client.

Released September 3, the fix keeps a failed iptables rule removal during steal-port teardown from taking down all clients rather than only the one tearing down, a blast-radius bug for teams using mirrord to give agents a pod-like Kubernetes environment. It also keeps remote file operations working after an agent reconnect, and makes user-data updates atomic so concurrent processes and interrupted writes can't corrupt stored data. NATS was added as a queue type in split_queues.