The clone step named a repository that does not exist, so following the
procedure verbatim failed before reaching the install. The remote is
alexion/dotfiles.
Add docs/install.md, the operator runbook that turns the completed
neogaia Host into a running encrypted laptop from the NixOS live ISO:
push the flake to its remote, join wifi, clone the repo locally,
disko-install against neogaia with the chaotic substituter handed to the
install-time daemon, set the bootstrap login password by hand via
nixos-enter, and reboot.