feat: Add Kubernetes manifests for NetHack server

- Creates Kubernetes deployment, service, and PVC manifests to run a multiplayer NetHack server.
- Uses the pre-built matsuu/nethack-server:latest image.
- Configures the service to expose port 4000 externally and correctly route traffic to the container's port 23.
- Adds a .gitignore file to exclude temporary directories.

k8s/deployment.yaml

@@ -0,0 +1,34 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: nethack-server
+  namespace: nethack
+  labels:
+    app: nethack
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: nethack
+  template:
+    metadata:
+      labels:
+        app: nethack
+    spec:
+      containers:
+      - name: nethack
+        image: matsuu/nethack-server:latest
+        ports:
+        - containerPort: 23
+        env:
+        - name: DGL_PORT
+          value: "4000"
+        - name: DGL_HOST
+          value: "0.0.0.0"
+        volumeMounts:
+        - name: nethack-data
+          mountPath: /opt/nethack/data
+      volumes:
+      - name: nethack-data
+        persistentVolumeClaim:
+          claimName: nethack-pvc