Renews Gmail Pub/Sub watches for all apestaart accounts (watches expire after 7 days). Systemd: apestaart_watch.service (Type=oneshot) + apestaart_watch.timer (OnUnitActiveSec=518400s ≈ 6 days, Persistent=true). Calls POST http://localhost:8000/webhooks/gmail/renew on the local apestaart_api_prod service. Runs via /usr/services/service_exec.sh wrapper, target /usr/services/apestaart_watch/start.sh.