add vaultwarden daily backup CronJob to NFS

SQLite backup via Online Backup API + copy of RSA keys,
attachments, sends, and config. 30-day retention with rotation.
Pod affinity ensures co-scheduling with vaultwarden for RWO PVC access.

stacks/platform/modules/iscsi-csi/main.tf

@@ -2,7 +2,8 @@ resource "kubernetes_namespace" "iscsi_csi" {
   metadata {
     name = "iscsi-csi"
     labels = {
-      tier = var.tier
+      tier                                  = var.tier
+      "resource-governance/custom-quota"     = "true"
     }
   }
 }