feat(data): Add CNPG cluster + database schema initialization

Create production PostgreSQL cluster via CNPG (3-node HA, Longhorn storage).

Schema initialization Job creates schemas for:
- Authentik (identity provider)
- Temporal (workflow engine)
- Vault (secrets management)
- App (generic application databases)

Database layer now captures complete IaC for stateful infrastructure.
Services find ready schemas when deployed.

k8s/data/db-init-job.yaml

@@ -0,0 +1,67 @@
+apiVersion: batch/v1
+kind: Job
+metadata:
+  name: db-schema-init
+  namespace: ddb
+  labels:
+    app: postgresql-init
+    layer: data
+spec:
+  backoffLimit: 3
+  ttlSecondsAfterFinished: 3600  # Keep Job for 1 hour after completion
+  template:
+    metadata:
+      labels:
+        app: postgresql-init
+    spec:
+      serviceAccountName: default
+      restartPolicy: Never
+      containers:
+      - name: schema-init
+        image: postgres:16.2-alpine
+        env:
+        - name: PGHOST
+          value: ddb-cluster-rw.ddb.svc.cluster.local
+        - name: PGPORT
+          value: "5432"
+        - name: PGDATABASE
+          value: app
+        - name: PGUSER
+          value: app
+        - name: PGPASSWORD
+          valueFrom:
+            secretKeyRef:
+              name: ddb-cluster-app
+              key: password
+        command:
+        - /bin/sh
+        - -c
+        - |
+          # Wait for cluster to be ready
+          echo "Waiting for PostgreSQL to be ready..."
+          until pg_isready -h $PGHOST -p $PGPORT -U $PGUSER; do
+            echo "Waiting..."
+            sleep 5
+          done
+
+          echo "Creating schemas..."
+
+          # Create schemas from ConfigMap
+          psql -h $PGHOST -p $PGPORT -U $PGUSER -d $PGDATABASE << 'EOF'
+          CREATE SCHEMA IF NOT EXISTS authentik;
+          GRANT USAGE ON SCHEMA authentik TO app;
+          GRANT CREATE ON SCHEMA authentik TO app;
+
+          CREATE SCHEMA IF NOT EXISTS temporal;
+          GRANT USAGE ON SCHEMA temporal TO app;
+          GRANT CREATE ON SCHEMA temporal TO app;
+
+          CREATE SCHEMA IF NOT EXISTS vault;
+          GRANT USAGE ON SCHEMA vault TO app;
+          GRANT CREATE ON SCHEMA vault TO app;
+
+          GRANT USAGE ON SCHEMA public TO app;
+          GRANT CREATE ON SCHEMA public TO app;
+          EOF
+
+          echo "✓ Schema initialization complete"

k8s/data/ddb-cluster.yaml

@@ -0,0 +1,62 @@
+apiVersion: postgresql.cnpg.io/v1
+kind: Cluster
+metadata:
+  name: ddb-cluster
+  namespace: ddb
+  labels:
+    app: postgresql
+    layer: data
+spec:
+  # 3-node cluster for HA
+  instances: 3
+
+  # PostgreSQL 16.2
+  imageName: ghcr.io/cloudnative-pg/postgresql:16.2
+
+  # Bootstrap: create app database + extensions
+  bootstrap:
+    initdb:
+      database: app
+      owner: app
+      encoding: UTF8
+      localeCollate: C
+      localeCType: C
+      postInitApplicationSQL:
+        - CREATE EXTENSION IF NOT EXISTS vector;
+        - CREATE EXTENSION IF NOT EXISTS pgcrypto;
+        - CREATE EXTENSION IF NOT EXISTS pg_trgm;
+
+  # Disable superuser (security)
+  enableSuperuserAccess: false
+
+  # PostgreSQL configuration
+  postgresql:
+    parameters:
+      shared_buffers: "256MB"
+      max_parallel_workers: "4"
+      max_parallel_workers_per_gather: "4"
+      # WAL archiving for backups
+      archive_mode: "on"
+      archive_timeout: "5min"
+      log_destination: "csvlog"
+      log_directory: "/controller/log"
+      log_filename: "postgres"
+      log_rotation_age: "0"
+      dynamic_shared_memory_type: "posix"
+
+  # Storage on Longhorn
+  storage:
+    size: 10Gi
+    storageClass: longhorn
+
+  # Monitoring
+  monitoring:
+    enablePodMonitor: false
+    disableDefaultQueries: false
+    customQueriesConfigMap:
+      - name: cnpg-default-monitoring
+        key: queries
+
+  # Pod anti-affinity for spreading replicas
+  affinity:
+    podAntiAffinityType: preferred

k8s/data/kustomization.yaml

@@ -4,9 +4,12 @@ metadata:
   name: data
 
 # Layer 6: Data — stateful services (databases, message brokers)
-# Dependencies: all previous layers
+# Dependencies: all previous layers (bootstrap, platform, etc.)
 # Order: Applied last
 
-# Placeholder for future database deployments
+# PostgreSQL cluster + schema initialization
-# Currently empty; databases deployed via Layer 5 applications
+# Required by: Authentik, Temporal, Vault, SQS
-resources: []
+resources:
+  - ddb-cluster.yaml
+  - schemas.yaml
+  - db-init-job.yaml

k8s/data/schemas.yaml

@@ -0,0 +1,36 @@
+---
+# Schema initialization ConfigMap for PostgreSQL services
+# Services: Authentik, Vault (optional), Temporal, others
+# Applied via initdb Jobs after CNPG cluster is ready
+
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: db-schemas
+  namespace: ddb
+  labels:
+    app: postgresql-schemas
+data:
+  # Authentik schema (minimal — Authentik creates most tables via Django ORM)
+  authentik-init.sql: |
+    CREATE SCHEMA IF NOT EXISTS authentik;
+    GRANT USAGE ON SCHEMA authentik TO app;
+    GRANT CREATE ON SCHEMA authentik TO app;
+
+  # Temporal schema
+  temporal-init.sql: |
+    CREATE SCHEMA IF NOT EXISTS temporal;
+    GRANT USAGE ON SCHEMA temporal TO app;
+    GRANT CREATE ON SCHEMA temporal TO app;
+
+  # Vault schema (if using PostgreSQL backend)
+  vault-init.sql: |
+    CREATE SCHEMA IF NOT EXISTS vault;
+    GRANT USAGE ON SCHEMA vault TO app;
+    GRANT CREATE ON SCHEMA vault TO app;
+
+  # Application schema (generic)
+  app-init.sql: |
+    -- Default app schema (public)
+    GRANT USAGE ON SCHEMA public TO app;
+    GRANT CREATE ON SCHEMA public TO app;