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/namespaces.tf

@@ -27,3 +27,13 @@ resource "kubernetes_namespace" "external_secrets" {
     }
   }
 }
+
+resource "kubernetes_namespace" "mudcraft" {
+  metadata {
+    name = "mudcraft"
+    labels = {
+      managed-by = "terraform"
+      tier       = "game"
+    }
+  }
+}