REFACTOR(postgresql): rename pg-cnpg namespace and folder

- Rename to postgresql
- Standardize naming convention

postgresql/kustomization.yaml

@@ -0,0 +1,20 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+namespace: postgresql
+
+resources:
+  # Vault External Secrets
+  - vault/app-user-secret.yaml
+  - vault/superuser-secret.yaml
+  - vault/vault-user-secret.yaml
+  # - vault/backup-s3-secret.yaml  # Disabled - using Velero instead
+
+  # CNPG Cluster
+  - manifests/cluster.yaml
+  - manifests/vault-database.yaml
+
+  # PodMonitor is auto-created by CNPG operator via cluster.spec.monitoring.enablePodMonitor
+
+  # Scheduled Backup - Disabled, using Velero instead
+  # - manifests/scheduled-backup.yaml