fix: proxmox_upgrade loop_var syntax

roles/proxmox_upgrade/tasks/main.yml

@@ -2,7 +2,6 @@
 # =============================================================================
 # proxmox_upgrade — main.yml
 # Orchestrates rolling Proxmox cluster upgrade
-# Runs on the first node in upgrade_order, delegates API calls to localhost
 # =============================================================================
 
 - name: Proxmox Upgrade | Start
@@ -23,11 +22,11 @@
 - name: Proxmox Upgrade | Rolling upgrade loop
   include_tasks: node_upgrade.yml
   loop: "{{ upgrade_order }}"
-  loop_var: current_node
+  loop_control:
+    loop_var: current_node
 
 - name: Proxmox Upgrade | Complete
   ansible.builtin.debug:
     msg: >-
       Proxmox rolling upgrade complete for {{ client_name }}
       — all {{ upgrade_order | length }} nodes upgraded successfully
-