Mount only xmpp cert dirs to fix letsencrypt permission errors

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>

docker-compose.yml

@@ -23,7 +23,8 @@ services:
       - ./data/prosody:/var/lib/prosody
       - ./logs/prosody:/var/log/prosody
       - ./data/prosody/configuration:/etc/prosody/conf.d
-      - /etc/letsencrypt:/etc/prosody/certs/letsencrypt:ro
+      - /etc/letsencrypt/live/xmpp.guschin.info:/etc/prosody/certs/letsencrypt/live/xmpp.guschin.info:ro
+      - /etc/letsencrypt/archive/xmpp.guschin.info:/etc/prosody/certs/letsencrypt/archive/xmpp.guschin.info:ro
     restart: unless-stopped
     mem_limit: 200M
     healthcheck: