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/postgres/postgres-service.yaml

@@ -0,0 +1,13 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: postgres
+  labels:
+    app: postgres
+spec:
+  selector:
+    app: postgres
+  ports:
+  - name: postgres
+    targetPort: postgres
+    port: 5432