[ci skip] migrate Redis, Prometheus, Loki storage to iSCSI

- Redis: local-path → iscsi-truenas (master + replica persistence)
- Prometheus: NFS PV+PVC → dynamic iSCSI PVC (prometheus-data)
- Loki: NFS PV → dynamic iSCSI via storageClass in Helm values
- Deleted 2 orphaned Released iSCSI PVs (31Gi freed)

stacks/platform/modules/redis/main.tf

@@ -60,7 +60,7 @@ resource "helm_release" "redis" {
     master = {
       persistence = {
         enabled      = true
-        storageClass = "local-path"
+        storageClass = "iscsi-truenas"
         size         = "2Gi"
       }
 
@@ -81,7 +81,7 @@ resource "helm_release" "redis" {
 
       persistence = {
         enabled      = true
-        storageClass = "local-path"
+        storageClass = "iscsi-truenas"
         size         = "2Gi"
       }