fix: set storageClassName=local-path in PVC patch to match live cluster

kubectl apply computes a 3-way merge. The base PVC has no storageClassName
(nil), but the already-bound PVC in the cluster has storageClassName=local-path.
This diff caused apply to attempt a mutation on a bound PVC — forbidden by k8s.

Fix: patch the PVC with storageClassName=local-path so desired state matches
live state and apply produces no diff on the PVC.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

k8s/overlays/on-premise/mysql-pvc-patch.yaml

@@ -3,8 +3,10 @@ kind: PersistentVolumeClaim
 metadata:
   name: mysql-data-pvc
 spec:
-  storageClassName: manual
-  volumeName: mysql-pv
+  # Must explicitly match the storageClassName already on the live PVC.
+  # Without this, kubectl apply diffs nil (base has no field) vs "local-path"
+  # (cluster) and tries to mutate a bound PVC — which Kubernetes forbids.
+  storageClassName: local-path
   accessModes:
     - ReadWriteOnce
   resources: