Users can now register as name@guschin.info or name@xmpp.guschin.info.
Added Let's Encrypt cert mounting and install for guschin.info domain.
Refactored entrypoint cert install into reusable function.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Mount specific live/ and archive/ subdirectories instead of all of
/etc/letsencrypt to avoid Prosody scanning root-only directories
(accounts/, archive/ for other domains). Also remove allow_registration.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
