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/k8s/mudcraft/statefulset.yaml

@@ -0,0 +1,89 @@
+---
+apiVersion: apps/v1
+kind: StatefulSet
+metadata:
+  name: mudcraft
+  namespace: mudcraft
+  labels:
+    app: mudcraft
+spec:
+  replicas: 1
+  serviceName: mudcraft
+  selector:
+    matchLabels:
+      app: mudcraft
+  template:
+    metadata:
+      labels:
+        app: mudcraft
+    spec:
+      terminationGracePeriodSeconds: 120
+      containers:
+        - name: mudcraft
+          image: itzg/minecraft-server:java21
+          imagePullPolicy: Always
+          ports:
+            - name: minecraft
+              containerPort: 25565
+              protocol: TCP
+            - name: rcon
+              containerPort: 25575
+              protocol: TCP
+          envFrom:
+            - configMapRef:
+                name: mudcraft-config
+          env:
+            - name: RCON_PASSWORD
+              valueFrom:
+                secretKeyRef:
+                  name: mudcraft-secrets
+                  key: rcon-password
+            - name: DB_URL
+              value: "jdbc:postgresql://postgres-postgresql.platform.svc.cluster.local:5432/mudcraft"
+            - name: DB_USER
+              value: "mudcraft"
+            - name: DB_PASSWORD
+              valueFrom:
+                secretKeyRef:
+                  name: mudcraft-secrets
+                  key: db-password
+          volumeMounts:
+            - name: worlds
+              mountPath: /data/worlds
+            - name: plugins
+              mountPath: /data/plugins
+            - name: logs
+              mountPath: /data/logs
+          resources:
+            requests:
+              memory: 7Gi
+              cpu: 2000m
+            limits:
+              memory: 8Gi
+              cpu: 6000m
+          lifecycle:
+            preStop:
+              exec:
+                command: ["/bin/sh", "-c", "rcon-cli stop && sleep 15"]
+          readinessProbe:
+            tcpSocket:
+              port: 25565
+            initialDelaySeconds: 60
+            periodSeconds: 15
+            failureThreshold: 10
+          livenessProbe:
+            tcpSocket:
+              port: 25565
+            initialDelaySeconds: 120
+            periodSeconds: 30
+            failureThreshold: 5
+      volumes:
+        - name: worlds
+          persistentVolumeClaim:
+            claimName: mudcraft-worlds
+        - name: plugins
+          persistentVolumeClaim:
+            claimName: mudcraft-plugins
+        - name: logs
+          persistentVolumeClaim:
+            claimName: mudcraft-logs