fix(longhorn): hardcode StorageClass numberOfReplicas to quoted "3"

The un-suspend reconcile stalled: platform Kustomization Ready=False with
'StorageClass/longhorn ... .parameters.numberOfReplicas: expected string, got 3'.
StorageClass.parameters is map[string]string, but kustomize strips the quotes
around the bare "${LONGHORN_DEFAULT_REPLICA_COUNT}" placeholder, so Flux postBuild
substitution produced an unquoted numeric that server-side apply rejects as int.
Hardcode the quoted numeric literal "3" (kustomize preserves those, as "30" shows);
topology is locked at 3 nodes. The replica knob still drives the global default via
defaultSettings.defaultReplicaCount in the helmrelease (a Helm int value, unaffected).

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

platform/longhorn/storageclasses.yaml

@@ -16,10 +16,15 @@ allowVolumeExpansion: true
 reclaimPolicy: Delete            # dev: reclaim space when the PVC is deleted
 volumeBindingMode: Immediate
 parameters:
-  # 3 replicas across 3 nodes — substituted from cluster-vars.longhorn_default_replica_count.
-  # HARD node anti-affinity in helmrelease.yaml (replicaSoftAntiAffinity=false) guarantees these
-  # replicas land on distinct nodes, so any single node loss keeps the volume available.
-  numberOfReplicas: "${LONGHORN_DEFAULT_REPLICA_COUNT}"
+  # 3 replicas across 3 nodes (topology-LOCKED). HARD node anti-affinity in helmrelease.yaml
+  # (replicaSoftAntiAffinity=false) guarantees these land on distinct nodes, so any single node
+  # loss keeps the volume available.
+  # HARDCODED, not ${LONGHORN_DEFAULT_REPLICA_COUNT}: StorageClass.parameters is map[string]string,
+  # but kustomize strips the quotes around a bare "${VAR}" placeholder, so Flux postBuild substitution
+  # yields an unquoted numeric (3) that server-side apply rejects (int, not string). A quoted numeric
+  # literal like "3"/"30" IS preserved by kustomize. The replica knob still drives the GLOBAL default
+  # via defaultSettings.defaultReplicaCount in helmrelease.yaml (a Helm int value, unaffected).
+  numberOfReplicas: "3"
   staleReplicaTimeout: "30"      # minutes before a down replica is considered stale and rebuilt
   dataLocality: "disabled"       # keep replicas spread for durability, not co-located with the pod
   fsType: "ext4"