refactor(ingress): rename packwiz.* subdomain to pack.*

Rename the pack-serving vhost/alias from packwiz.${BASE_DOMAIN} to
pack.${BASE_DOMAIN} (caddy conf, caddy network alias, PACKWIZ_URL).
Inline the static-site caddy mounts (10-static.caddy, www, launcher,
CA cert) into the base compose; set MOTD to "Uli LAN party".

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

caddy/conf.d/00-core.caddy

@@ -3,7 +3,7 @@ http://auth.{$BASE_DOMAIN} {
 	reverse_proxy drasl:25585
 }
 
-http://packwiz.{$BASE_DOMAIN} {
+http://pack.{$BASE_DOMAIN} {
 	root * /srv/pack
 	file_server browse
 }