The sops secret declarations, the empty `hostKeys`, and the `HostKey`
lines were boilerplate sitting in the host, and every future host
restoring its identity would have repeated them.
`modules.ssh` takes the encrypted file and the key types, deriving the
secret names and the `HostKey` lines from one list, so the daemon and the
secrets cannot disagree about where a key lives. The resulting system
derivation is unchanged.
Also record two gotchas: reading PR review comments needs the Gitea API
rather than tea, and host keys are not user authentication keys.
The host's SSH identity was generated by the daemon, so reimaging the
laptop would invalidate it and break `known_hosts` for every client that
had ever connected.
Add `secrets/neogaia.yaml`, the first per-host secrets file, encrypted to
the admin identity and `neogaia` alone so a compromised machine cannot
decrypt another's material. It holds both host private keys; the public
halves are committed in plaintext.
Clear `services.openssh.hostKeys` to stop generation and point `HostKey`
at the decrypted paths. These are ordinary secrets rather than the
pre-user ones the password uses, exercising the second decryption path.
