feat(deploy): k8s manifests for microk8s (vncmail.sandbox.vnc.de)

Bulwark is stateful (local /app/data) — Vercel serverless (read-only fs)
crashes it. Deploy as a container with 4 persistent volumes on microk8s,
alongside bulwark.sandbox.vnc.de. Adds deploy/k8s/ (namespace, pvc, deployment,
service, ingress, secret template, runbook) + rewrites setup doc off Vercel.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

deploy/k8s/deployment.yaml

@@ -0,0 +1,87 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: vncmail-plus
+  namespace: vncmail
+  labels:
+    app: vncmail-plus
+spec:
+  replicas: 1
+  selector:
+    matchLabels:
+      app: vncmail-plus
+  # RWO volumes can only mount to one pod — Recreate avoids a stuck rollout.
+  strategy:
+    type: Recreate
+  template:
+    metadata:
+      labels:
+        app: vncmail-plus
+    spec:
+      # The image runs as uid/gid 1001 (nextjs:nodejs) and the Dockerfile
+      # chowns /app/data to 1001. fsGroup makes the mounted PVCs writable by it.
+      securityContext:
+        fsGroup: 1001
+        runAsUser: 1001
+        runAsGroup: 1001
+      # ghcr package is private by default — see deploy/k8s/README.md to create
+      # this pull secret. Delete this block if you make the package public.
+      imagePullSecrets:
+        - name: ghcr-pull
+      containers:
+        - name: vncmail-plus
+          # dev image (built from the `dev` branch by CI). For production pin a
+          # digest: ghcr.io/brvncde-dotcom/vncmail-plus-dev@sha256:<digest>
+          image: ghcr.io/brvncde-dotcom/vncmail-plus-dev:latest
+          imagePullPolicy: Always
+          ports:
+            - containerPort: 3000
+          envFrom:
+            - secretRef:
+                name: vncmail-env
+          env:
+            - name: HOSTNAME
+              value: "0.0.0.0"
+            - name: PORT
+              value: "3000"
+          readinessProbe:
+            httpGet:
+              path: /api/health
+              port: 3000
+            initialDelaySeconds: 10
+            periodSeconds: 10
+          livenessProbe:
+            httpGet:
+              path: /api/health
+              port: 3000
+            initialDelaySeconds: 25
+            periodSeconds: 30
+          resources:
+            requests:
+              cpu: 100m
+              memory: 256Mi
+            limits:
+              cpu: "1"
+              memory: 1Gi
+          volumeMounts:
+            - name: settings
+              mountPath: /app/data/settings
+            - name: admin
+              mountPath: /app/data/admin
+            - name: admin-state
+              mountPath: /app/data/admin-state
+            - name: telemetry
+              mountPath: /app/data/telemetry
+      volumes:
+        - name: settings
+          persistentVolumeClaim:
+            claimName: vncmail-settings
+        - name: admin
+          persistentVolumeClaim:
+            claimName: vncmail-admin
+        - name: admin-state
+          persistentVolumeClaim:
+            claimName: vncmail-admin-state
+        - name: telemetry
+          persistentVolumeClaim:
+            claimName: vncmail-telemetry