Local Postgres, peer-authed over the unix socket (the "zitadel" role is
granted createdb+createrole and doubles as both the runtime and bootstrap
DB user - no password anywhere). TLS terminates at Caddy; Zitadel listens
on localhost:8080 and is proxied at auth.mgaction.town.
Master key and admin bootstrap password come from sops - the admin
password specifically needs the sops.templates -> rendered-file route
(services.zitadel.steps would leak it into the world-readable Nix store),
same pattern as mercury's pihole.env.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>