Add k8s deployment, standalone app Dockerfile.

Tested with Rancher k3s. See k8s/README.md for site configuration and
deployment instructions.

Add cert-manager, tls, remote headscale script.

k8s/base/service.yaml

@@ -0,0 +1,13 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: headscale
+  labels:
+    app: headscale
+spec:
+  selector:
+    app: headscale
+  ports:
+  - name: http
+    targetPort: http
+    port: 8080