persist is admin in json user repo

app/User/JsonUserRepository.php

@@ -22,12 +22,14 @@ class JsonUserRepository implements UserRepository
         $users[] = [
             'id' => $id,
             'email' => (string) $dto->email,
+            'isAdmin' => $dto->isAdmin,
         ];
         $this->writeUsers($users);
 
         return new User(
             id: $id,
             email: $dto->email,
+            isAdmin: $dto->isAdmin,
         );
     }
 
@@ -40,6 +42,7 @@ class JsonUserRepository implements UserRepository
                 return new User(
                     id: $data['id'],
                     email: new EmailAddress($data['email']),
+                    isAdmin: $data['isAdmin'] ?? false,
                 );
             }
         }