feat(env): add BASE_DOMAIN + HOST_LAN_IP to .env.example

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.env.example

@@ -1,4 +1,10 @@
 # Copy to .env and fill in real values
+
+# Single base domain for the whole stack; every service is a subdomain of this.
+BASE_DOMAIN=ulicraft.local
+# The Docker host's LAN IP — dnsmasq points *.BASE_DOMAIN here for guest laptops.
+HOST_LAN_IP=192.168.1.10
+
 RCON_PASSWORD=change-me-to-something-random
 # Only needed if using CurseForge-exclusive mods:
 # CF_API_KEY=your-curseforge-api-key