Fix PageController variant template: add missing winnerCriteria and configurationError keys

The shared Variant/row.html.twig template expects winnerCriteria and
configurationError keys in the variants array. The EmailController passes
these via AbTestSettingsService, but PageController was missing them,
causing a 500 error on page detail view when variants exist.

Author: kuzmany

app/bundles/PageBundle/Controller/PageController.php

@@ -300,6 +300,8 @@ public function viewAction(Request $request, PageConfig $pageConfig, PageModel $
             'children'           => $children,
             'properties'         => $properties,
             'criteria'           => $criteria['criteria'],
+            'winnerCriteria'     => $lastCriteria ?? '',
+            'configurationError' => $variantError,
         ];
 
         $translations = [