feat(vocab): attach language names to course data in VocabService

- Added a method to attach language names to course rows, enhancing the clarity and localization of vocabulary lessons.
- This update improves the overall user experience by ensuring accurate representation of language names in course data.

backend/services/vocabService.js

@@ -1867,6 +1867,8 @@ export default class VocabService {
       pedagogy: this._buildLessonPedagogy(lesson)
     }));
 
+    await this._attachLanguageNamesToCourseRows([courseData]);
+
     return courseData;
   }