fix(longhorn): clear permanent OutOfSync on longhorn-config

StorageClass.parameters is immutable and mkfsParams was added after creation,
so every sync failed. Replace=true recreates it instead of patching. Existing
volumes keep their format; only new ones get mkfsParams.

Longhorn names its own disk key and writes storageReserved into it, so git's
default-disk never matched and selfHeal kept trying to add a second disk on the
same path. Dropped spec.disks from git, added ignoreDifferences.

k8s/infra/longhorn/longhorn-cnpg-storageclass.yaml

@@ -7,6 +7,22 @@ metadata:
   namespace: longhorn-system
   annotations:
     storageclass.kubernetes.io/is-default-class: "false"
+    # StorageClass.parameters is immutable. mkfsParams below was added after
+    # this class already existed, so every sync failed with
+    #   parameters: Invalid value: {...}: field is immutable
+    # and the Application sat OutOfSync permanently — ArgoCD retrying a change
+    # the API server can never accept.
+    #
+    # Replace=true makes ArgoCD delete and recreate instead of patching. Safe
+    # for a StorageClass: it is consulted only at provisioning time, so bound
+    # PVs and their data are untouched. New PVCs briefly fail if one is created
+    # during the window.
+    #
+    # Note what this does NOT do: the nine CNPG volumes already provisioned were
+    # formatted without mkfsParams and keep that format. Only volumes created
+    # after this recreate get it. Existing volumes that need to expand still
+    # need handling separately.
+    argocd.argoproj.io/sync-options: Replace=true,Force=true
 provisioner: driver.longhorn.io
 allowVolumeExpansion: true
 parameters: