Port CloudNative-PG off Helm to direct release manifest (#268)

## Summary
- Point ArgoCD app directly at forge-mirrored upstream repo (`mirrors/cloudnative-pg`) instead of the Helm charts repo
- Use `directory.include` to select the specific release manifest (`cnpg-1.27.1.yaml`) from the `releases/` directory
- No vendored files, no Helm — upgrades are a two-line change (`targetRevision` + `directory.include`)
- Delete unused `values.yaml` (was empty, all Helm defaults)

## Deployment and Testing
- [ ] Register mirror repo in ArgoCD: `argocd repo add ssh://forgejo@forge.ops.eblu.me:2222/mirrors/cloudnative-pg.git --ssh-private-key-path <key>`
- [ ] `argocd app set cloudnative-pg --revision feature/cnpg-direct-source && argocd app sync cloudnative-pg`
- [ ] Verify operator pod running: `kubectl get pods -n cnpg-system --context=minikube-indri`
- [ ] Verify CRDs exist: `kubectl get crd --context=minikube-indri | grep cnpg`
- [ ] Verify existing clusters healthy: `kubectl get clusters -A --context=minikube-indri`
- [ ] After merge: `argocd app set cloudnative-pg --revision main && argocd app sync cloudnative-pg`

## Notes
- The forge mirror was created via `mise run mirror-create` from `https://github.com/cloudnative-pg/cloudnative-pg.git`
- ArgoCD may need the mirror repo added to its known repositories if the credential template doesn't already match `mirrors/*`

Reviewed-on: https://forge.ops.eblu.me/eblume/blumeops/pulls/268

argocd/apps/cloudnative-pg.yaml

@@ -1,7 +1,7 @@
 # CloudNativePG Operator - PostgreSQL for Kubernetes
 # Deploys the operator only; PostgreSQL clusters are created separately
 #
-# Chart mirrored from https://github.com/cloudnative-pg/charts to forge
+# Mirror of https://github.com/cloudnative-pg/cloudnative-pg
 apiVersion: argoproj.io/v1alpha1
 kind: Application
 metadata:
@@ -9,19 +9,12 @@ metadata:
   namespace: argocd
 spec:
   project: default
-  sources:
-    # Helm chart from forge mirror (SSH via egress)
-    - repoURL: ssh://forgejo@forge.ops.eblu.me:2222/mirrors/cloudnative-pg-charts.git
-      targetRevision: cloudnative-pg-v0.27.1
-      path: charts/cloudnative-pg
-      helm:
-        releaseName: cloudnative-pg
-        valueFiles:
-          - $values/argocd/manifests/cloudnative-pg/values.yaml
-    # Values from our git repo
-    - repoURL: ssh://forgejo@forge.ops.eblu.me:2222/eblume/blumeops.git
-      targetRevision: main
-      ref: values
+  source:
+    repoURL: ssh://forgejo@forge.ops.eblu.me:2222/mirrors/cloudnative-pg.git
+    targetRevision: v1.27.1
+    path: releases
+    directory:
+      include: 'cnpg-1.27.1.yaml'
   destination:
     server: https://kubernetes.default.svc
     namespace: cnpg-system