[ci skip] openclaw: persist home directory on NFS

- Switch openclaw-home from emptyDir to NFS (/mnt/main/openclaw/home)
- Persists SOUL.md, IDENTITY.md, sessions, memory DB, telegram state,
  device identity, and all runtime files across pod restarts
- Init container still refreshes openclaw.json and kubeconfig on each start

stacks/openclaw/main.tf

@@ -524,7 +524,10 @@ resource "kubernetes_deployment" "openclaw" {
         }
         volume {
           name = "openclaw-home"
-          empty_dir {}
+          nfs {
+            server = var.nfs_server
+            path   = "/mnt/main/openclaw/home"
+          }
         }
         volume {
           name = "workspace"