Migrate Joplin to K3s and add existing k8s manifests

- New k8s/joplin/ deployment for note.expertfab.de (Postgres + Server +
  Traefik ingress with cert-manager), replicas=2 to match cluster size
- coredns-custom.yaml: route note.expertfab.de internally to Traefik LB
- Commit previously-built k8s manifests (documenso, erpnext oauth2-proxy,
  paperless oauth2-proxy) that were running but not in git
- docs/access.md: add Joplin section and Documenso/Cloudflare entries

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

k8s/joplin/joplin.yaml

@@ -0,0 +1,92 @@
+---
+apiVersion: v1
+kind: Secret
+metadata:
+  name: joplin-env
+  namespace: joplin
+type: Opaque
+stringData:
+  APP_BASE_URL: "https://note.expertfab.de"
+  APP_PORT: "22300"
+  DB_CLIENT: "pg"
+  POSTGRES_HOST: "joplin-postgres"
+  POSTGRES_PORT: "5432"
+  POSTGRES_DATABASE: "joplin"
+  POSTGRES_USER: "joplin"
+  POSTGRES_PASSWORD: "TXIlCX4DUdKZuqbYt2lTaxMXvz6cJi"
+  MAILER_ENABLED: "1"
+  MAILER_HOST: "smtprelay.expertfab.de"
+  MAILER_PORT: "587"
+  MAILER_SECURITY: "starttls"
+  MAILER_AUTH_USER: "it-admin@expertfab.de"
+  MAILER_AUTH_PASSWORD: "Relay22$$"
+  MAILER_NOREPLY_NAME: "ExpertFab Joplin"
+  MAILER_NOREPLY_EMAIL: "it-admin@expertfab.de"
+---
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: joplin
+  namespace: joplin
+spec:
+  replicas: 1
+  strategy:
+    type: RollingUpdate
+    rollingUpdate:
+      maxSurge: 1
+      maxUnavailable: 0
+  selector:
+    matchLabels:
+      app: joplin
+  template:
+    metadata:
+      labels:
+        app: joplin
+    spec:
+      containers:
+        - name: joplin
+          image: joplin/server:latest
+          ports:
+            - containerPort: 22300
+          envFrom:
+            - secretRef:
+                name: joplin-env
+          readinessProbe:
+            httpGet:
+              path: /api/ping
+              port: 22300
+              httpHeaders:
+                - name: Host
+                  value: note.expertfab.de
+            initialDelaySeconds: 30
+            periodSeconds: 10
+            failureThreshold: 6
+          livenessProbe:
+            httpGet:
+              path: /api/ping
+              port: 22300
+              httpHeaders:
+                - name: Host
+                  value: note.expertfab.de
+            initialDelaySeconds: 90
+            periodSeconds: 30
+            failureThreshold: 5
+          resources:
+            requests:
+              cpu: 100m
+              memory: 512Mi
+            limits:
+              cpu: 1000m
+              memory: 1500Mi
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: joplin
+  namespace: joplin
+spec:
+  selector:
+    app: joplin
+  ports:
+    - port: 22300
+      targetPort: 22300