fix: return JSON object instead of array for empty category restrictions

Empty PHP arrays serialize as JSON [] but the CategoryRestrictions
TypeScript interface expects an object ({[rightId: string]: number[]}).
Use stdClass to ensure {} is returned when there are no restrictions.

Author: thorsten

phpmyfaq/src/phpMyFAQ/Controller/Administration/Api/GroupController.php

@@ -145,10 +145,13 @@ public function listCategoryRestrictions(Request $request): JsonResponse
         $groupId = (int) $request->attributes->get('groupId');
 
         if (!$currentUser->perm instanceof MediumPermission) {
-            return $this->json([], Response::HTTP_OK);
+            return $this->json(new \stdClass(), Response::HTTP_OK);
         }
 
-        return $this->json($currentUser->perm->getAllCategoryRestrictions($groupId), Response::HTTP_OK);
+        return $this->json(
+            $currentUser->perm->getAllCategoryRestrictions($groupId) ?: new \stdClass(),
+            Response::HTTP_OK,
+        );
     }
 
     /**