2configs.retiolum: take host data from kartei directly
The daemon stays on nixpkgs services.tinc; only the host database moves.
stockholm pins a kartei from before barnacle and its host type still requires
the legacy RSA pubkey, so peer keys now come from kartei modules/retiolum/hosts.nix
instead of config.krebs.hosts. krebs.hosts is untouched for everything else
(dns, iptables, consul, ...).
Effects: barnacle and 5 newer hosts become known fleet-wide, and the 35
RSA-only entries drop out -- tincr is SPTPS-only and refused them once per
connection attempt anyway.
starkstrom has no kartei card and keeps the one it declares locally in
krebs.hosts; that fallback goes away once it is in kartei.