feat(infra): k3s foundation — cert-manager, Longhorn config, in-cluster data tier

Adds the production cluster foundation (authored + applied live on node1):
- cert-manager via the k3s HelmChart controller + letsencrypt staging/prod
  ClusterIssuers (HTTP-01 / Traefik).
- Longhorn config for single-node (values: replica=1, default StorageClass,
  Retain) + backup-to-Hetzner-Object-Storage credential template.
- In-cluster data tier (dezky-data): Postgres 16 (with Authentik+OCIS DB init),
  MongoDB 7, Redis 7 as StatefulSets on Longhorn, + secret template.
- bootstrap.sh: install open-iscsi/nfs-common + enable iscsid (Longhorn prereq).
- RUNBOOK.md: full reproducible node1 build order.

Real secrets are generated on-box and kept in Bitwarden — never in git.

infrastructure/production/fleet/data/postgres.yaml

@@ -0,0 +1,82 @@
+# PostgreSQL 16 — shared RDBMS for Authentik + OCIS (mirrors the dev stack).
+# Single-node StatefulSet on k3s local-path storage. Logical dumps for backup
+# are added by a pg_dump CronJob (Restic captures the dump dir on the host).
+apiVersion: v1
+kind: Service
+metadata:
+  name: postgres
+  namespace: dezky-data
+spec:
+  clusterIP: None          # headless: stable DNS postgres.dezky-data:5432
+  selector:
+    app: postgres
+  ports:
+    - name: postgres
+      port: 5432
+      targetPort: 5432
+---
+apiVersion: apps/v1
+kind: StatefulSet
+metadata:
+  name: postgres
+  namespace: dezky-data
+spec:
+  serviceName: postgres
+  replicas: 1
+  selector:
+    matchLabels:
+      app: postgres
+  template:
+    metadata:
+      labels:
+        app: postgres
+    spec:
+      # No fsGroup needed: the postgres image entrypoint runs as root and
+      # chowns PGDATA to the postgres user before stepping down.
+      containers:
+        - name: postgres
+          image: postgres:16-alpine
+          ports:
+            - containerPort: 5432
+          env:
+            - name: POSTGRES_USER
+              value: postgres
+            - name: PGDATA
+              value: /var/lib/postgresql/data/pgdata   # subdir avoids lost+found clash
+          envFrom:
+            - secretRef:
+                name: postgres-secret    # POSTGRES_PASSWORD, AUTHENTIK_DB_PASSWORD, OCIS_DB_PASSWORD
+          volumeMounts:
+            - name: data
+              mountPath: /var/lib/postgresql/data
+            - name: init
+              mountPath: /docker-entrypoint-initdb.d
+          resources:
+            requests:
+              cpu: 100m
+              memory: 256Mi
+            limits:
+              memory: 1Gi
+          readinessProbe:
+            exec:
+              command: ["pg_isready", "-U", "postgres"]
+            initialDelaySeconds: 10
+            periodSeconds: 10
+          livenessProbe:
+            exec:
+              command: ["pg_isready", "-U", "postgres"]
+            initialDelaySeconds: 30
+            periodSeconds: 20
+      volumes:
+        - name: init
+          configMap:
+            name: postgres-init
+  volumeClaimTemplates:
+    - metadata:
+        name: data
+      spec:
+        accessModes: ["ReadWriteOnce"]
+        storageClassName: longhorn
+        resources:
+          requests:
+            storage: 10Gi