Add the clan-core emergency-access service on all nixos machines; it
sets a per-machine recovery root password for console login when a
machine fails to boot.
- Knot authoritative DNS: ns1 primary, ns2 secondary serving cnx.network,
buildfor.life and cnx.email over TSIG-secured zone transfer (modules/dns)
- Knot listens publicly + over ZeroTier; firewall opens port 53
- Complete clan inventory: name/domain, admin SSH key, control as the
zerotier controller, tor on all nixos machines
- Enable age yubikey/fido2-hmac secret plugins