One radicle-node serves one keypair, so each machine that does radicle
work gets its own identity (vars generator `rad`) and a node running
as the `rad` system user over /var/lib/rad. The profile is group-shared
(setgid dirs, umask-002 wrappers for rad/git-remote-rad, pre-created
group-writable sqlite files) so any account in group `rad` signs with
the machine identity; mainUser is a member. RAD_HOME points there for
login shells. Imported explicitly on coaxmetal, neoprism, ignavia,
icarus and shodan.

Rename the public seed module to 2configs/radicle.lassul.us.nix and
switch its retired seed.radicle.garden entry to iris.radicle.network.