fix(vm_provision_mixin): destroy_vm's delete call rejected by Proxmox (400)

Passed destroy_unreferenced_disks (underscore) as a kwarg to proxmoxer's
delete(), but Proxmox's actual DELETE /nodes/{node}/qemu/{vmid} parameter
is hyphenated (destroy-unreferenced-disks). proxmoxer forwards kwargs to
the request verbatim with no underscore-to-hyphen translation, so Proxmox
rejected every call with "property is not defined in schema" before ever
touching the VM — the VM stayed fully intact (config, disks) despite the
caller believing destroy had at least been attempted. Fixed by building
the params as a dict (bypassing the Python-identifier restriction) with
the correct hyphenated key.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

napalm_proxmox/vm_provision_mixin.py

@@ -476,11 +476,16 @@ class ProxmoxVMProvisionMixin:
                 _logger.debug(f"VM {vmid} stop failed (may already be stopped): {e}")
 
             # Step 2: Delete VM
+            # Proxmox's API parameter is hyphenated (destroy-unreferenced-disks),
+            # not a valid Python identifier — proxmoxer forwards kwargs to the
+            # request verbatim with no underscore-to-hyphen translation, so this
+            # must be built as a dict and unpacked rather than passed as a kwarg.
             _logger.debug(f"Deleting VM {vmid} configuration and disks")
-            self._node_api().qemu(vmid_int).delete(
-                purge=1,
-                destroy_unreferenced_disks=1 if remove_disk else 0,
-            )
+            delete_params = {
+                "purge": 1,
+                "destroy-unreferenced-disks": 1 if remove_disk else 0,
+            }
+            self._node_api().qemu(vmid_int).delete(**delete_params)
 
             # Step 3: Clean up Cloud-Init snippets
             # (This is best-effort; snippet files may be unreachable if storage is unavailable)