Add MUDCraft Minecraft server infrastructure

- Purpur 1.21.4 server via itzg/docker-minecraft-server (java21)
- StatefulSet with 3 PVCs: worlds (20Gi), plugins (5Gi), logs (5Gi)
- Aikar G1GC JVM flags, 6GB heap (sized for Legion's 15GB RAM)
- Postgres: mudcraft database + user in existing platform/postgres
- RCON secret + DB password via ExternalSecret → Vault
- Traefik TCP entrypoint on port 25565 for mudcraft.nook.family
- mudcraft namespace via Terraform
- Argo CD app watching k8s/mudcraft/

servers/legion/traefik.tf

@@ -19,6 +19,12 @@ resource "kubernetes_manifest" "traefik_config" {
           web:
             redirectTo:
               port: websecure
+          minecraft:
+            port: 25565
+            expose:
+              default: true
+            exposedPort: 25565
+            protocol: TCP
       YAML
     }
   }