Fix: use queryTimed instead of undefined $pdo for ImageExtension update

$pdo doesn't exist in this file — all DB queries use queryTimed/queryOne
from helpers.php.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

api/setup/saveWizard.php

@@ -667,7 +667,7 @@ try {
             if (!is_dir($itemsDir)) mkdir($itemsDir, 0755, true);
             if (downloadItemImage($menuItemID, $itemImageUrl, $itemsDir)) {
                 $totalImages++;
-                $pdo->prepare("UPDATE Items SET ImageExtension = 'jpg' WHERE ID = ?")->execute([$menuItemID]);
+                queryTimed("UPDATE Items SET ImageExtension = 'jpg' WHERE ID = ?", [$menuItemID]);
             }
         }
     }