chore: remove pack (packwiz) service and subdomain

The pack service was already gone from compose/caddy and the landing is
off packwiz. Remove the remaining live references: the pack. TLS vhost in
the host nginx template, pack from LE_SUBDOMAINS, and stale docs in README
and CLAUDE.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.env.example

@@ -2,7 +2,7 @@
 
 # Single base domain for the whole stack; every service is a subdomain of this.
 # DNS is handled OUTSIDE this repo — point ${BASE_DOMAIN} and every subdomain
-# (auth. pack. avatar. status. distribution. www.) at the host running nginx.
+# (auth. avatar. status. distribution. www.) at the host running nginx.
 BASE_DOMAIN=ulicraft.net
 
 RCON_PASSWORD=change-me-to-something-random
@@ -56,7 +56,7 @@ DISTRIBUTION_WEB_ROOT=/home/oier/projects/mc-mods/ulicraft-group/ulicraft-distri
 # Only needed to issue real TLS certs. DNS-01 needs no inbound ports.
 LE_EMAIL=you@example.com
 # space-separated subdomains; apex ${BASE_DOMAIN} is always included
-LE_SUBDOMAINS=auth pack distribution www avatar status
+LE_SUBDOMAINS=auth distribution www avatar status
 # OVH API creds (DNS zone write). Create at https://eu.api.ovh.com/createToken/
 # OVH_CK can be blank on first run — acme.sh prints an auth URL, then paste it.
 OVH_END_POINT=ovh-eu