coturn started up cleanly every time (all TCP/UDP listeners on 3478/5349
opened fine per logs) but was killed every ~10s because the liveness
probe ran "netstat -uln", which doesn't exist in coturn/coturn:latest
(sh: netstat: not found) - 36000+ restarts over 88 days for a healthy
process. Switched to a tcpSocket probe against the TCP listener coturn
already opens on 3478, no in-container tooling required.