feat(dnsmasq): SRV record so clients connect to mc.<domain> without a port

Minecraft is a custom TCP protocol, not HTTP, so the no-port UX is solved with
a DNS SRV record (_minecraft._tcp.mc.<domain> -> :25565) rather than an HTTP
reverse proxy. Landing page now shows the bare address.

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

landing/src/data/site.ts

@@ -7,8 +7,9 @@ export const site = {
   tagline: "LAN-party Minecraft server",
   baseDomain: BASE_DOMAIN,
 
-  // Connect target shown to guests.
-  serverAddress: `mc.${BASE_DOMAIN}:25565`,
+  // Connect target shown to guests. No port needed — a dnsmasq SRV record
+  // (_minecraft._tcp.mc.<domain>) points clients at 25565.
+  serverAddress: `mc.${BASE_DOMAIN}`,
 
   // Drasl auth web UI + authlib-injector API root.
   authUrl: `http://auth.${BASE_DOMAIN}`,