Refactor helper drift in lib: centralize theme/translation and remove app() hotspots

lib/Service/User/UserLifecycleRestoreService.php

@@ -14,7 +14,8 @@ class UserLifecycleRestoreService
         private readonly UserReadRepositoryInterface $userReadRepository,
         private readonly UserWriteRepositoryInterface $userWriteRepository,
         private readonly UserLifecycleAuditService $userLifecycleAuditService,
-        private readonly DatabaseSessionRepository $databaseSessionRepository
+        private readonly DatabaseSessionRepository $databaseSessionRepository,
+        private readonly UserSettingsGateway $userSettingsGateway
     ) {
     }
 
@@ -171,8 +172,7 @@ class UserLifecycleRestoreService
 
     private function normalizeTheme(mixed $value): string
     {
-        $theme = strtolower(trim((string) $value));
-        $themes = appThemes();
-        return isset($themes[$theme]) ? $theme : appDefaultTheme();
+        $theme = is_scalar($value) ? (string) $value : null;
+        return $this->userSettingsGateway->normalizeTheme($theme);
     }
 }