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.

.gitignore

@@ -0,0 +1,3 @@
+# Temporary directories used for troubleshooting
+nethack-repo/
+nethack-server-docker/