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/ingress.yaml

@@ -0,0 +1,18 @@
+apiVersion: networking.k8s.io/v1
+kind: Ingress
+metadata:
+  name: headscale
+  annotations:
+    kubernetes.io/ingress.class: traefik
+spec:
+  rules:
+  - host: $(PUBLIC_HOSTNAME)
+    http:
+      paths:
+      - backend:
+          service:
+            name: headscale
+            port:
+              number: 8080
+        path: /
+        pathType: Prefix