deploy-agent.sh now self-heals the three postinst failure modes found on
PMG/PBS hosts (MANAGER_IP placeholder, missing wazuh user, root:root
ownership). scripts/disable-ipv6.sh: live sysctl + persisted conf, with
in-file rollback notes. Rollout state in #335/#748.
Meat: https://projects.knownelement.com/issues/335#note-4008