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/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
-# Currently empty; databases deployed via Layer 5 applications
-resources: []
+# PostgreSQL cluster + schema initialization
+# Required by: Authentik, Temporal, Vault, SQS
+resources:
+  - ddb-cluster.yaml
+  - schemas.yaml
+  - db-init-job.yaml