Add Authentik identity provider deployment

- Helm chart authentik 2026.5.3 with 3 server replicas, 2 worker replicas
- CNPG PostgreSQL cluster (3 instances) with rw and ro poolers (2 instances each)
- Redis with 5Gi persistent storage
- Gateway API: identity.unkin.net and identity.k8s.syd1.au.unkin.net (HTTPS)
- LDAPS via TLSRoute on ldap.k8s.syd1.au.unkin.net and ldap.main.unkin.net
- Multi-SAN TLS via cert-manager gateway integration
- S3 storage via RadosGW (bucket: authentik)
- Vault secrets: postgres-credentials, authentik-credentials, s3-credentials
- Woodpecker ServiceAccount for terraform-authentik CI
- Platform applicationset and project updated

apps/base/woodpecker/kustomization.yaml

@@ -7,6 +7,7 @@ resources:
   - cnpg_cluster.yaml
   - cnpg_pooler.yaml
   - serviceaccount_terraform_artifactapi.yaml
+  - serviceaccount_terraform_authentik.yaml
   - serviceaccount_terraform_git.yaml
   - serviceaccount_terraform_vault.yaml
   - vaultauth.yaml