The operator's SSH client key existed only as a file created by hand on one
laptop, so a reimage would destroy it and lock the operator out of the remote.
It now lives in neogaia's own secrets file, encrypted to the admin identity and
neogaia alone, and the client is pointed at the decrypted path rather than a
copy in the user's home.
Access becomes a policy over roles instead of a per-host list of keys. A new
fleet declaration names each machine's role and client public key, and every
machine derives what it authorizes from that: a workstation admits workstations
alone, a server admits both, so a compromised server reaches no machine of the
operator's own. Registering a machine is an entry in that one file.
Only neogaia exists, so the server half of the policy is built rather than
exercised. Two assertions reject a machine missing from the fleet and any entry
whose role no policy defines.
