feat(admin): add user vocab course management functionality

- Implemented `getUserVocabCourses` and `getVocabCourseForAdmin` methods in `AdminController` to allow admins to retrieve enrolled vocab courses for users and specific course details, respectively.
- Updated `adminRouter` to include new routes for accessing user vocab courses and course details.
- Enhanced `AdminService` with methods to list user-enrolled vocab courses and retrieve course information with lessons, ensuring proper access control.
- Improved `VocabService` to support the new functionalities, including attaching language names to course data.
- Updated UI components in `UsersView` to reflect changes, including error handling and loading states for course retrieval, along with localization updates for new features.

backend/controllers/adminController.js

@@ -34,6 +34,8 @@ class AdminController {
         this.getUsers = this.getUsers.bind(this);
         this.updateUser = this.updateUser.bind(this);
         this.resetUserVocabLessonProgress = this.resetUserVocabLessonProgress.bind(this);
+        this.getUserVocabCourses = this.getUserVocabCourses.bind(this);
+        this.getVocabCourseForAdmin = this.getVocabCourseForAdmin.bind(this);
         this.getAdultVerificationRequests = this.getAdultVerificationRequests.bind(this);
         this.setAdultVerificationStatus = this.setAdultVerificationStatus.bind(this);
         this.getAdultVerificationDocument = this.getAdultVerificationDocument.bind(this);
@@ -149,6 +151,30 @@ class AdminController {
         }
     }
 
+    async getUserVocabCourses(req, res) {
+        try {
+            const { userid: requester } = req.headers;
+            const { id } = req.params;
+            const result = await AdminService.adminListUserEnrolledVocabCourses(requester, id);
+            res.status(200).json(result);
+        } catch (err) {
+            const status = err.message === 'noaccess' ? 403 : (err.message === 'notfound' ? 404 : 500);
+            res.status(status).json({ error: err.message });
+        }
+    }
+
+    async getVocabCourseForAdmin(req, res) {
+        try {
+            const { userid: requester } = req.headers;
+            const { courseId } = req.params;
+            const result = await AdminService.adminGetVocabCourseWithLessons(requester, courseId);
+            res.status(200).json(result);
+        } catch (err) {
+            const status = err.message === 'noaccess' ? 403 : (err.message === 'coursenotfound' ? 404 : 500);
+            res.status(status).json({ error: err.message });
+        }
+    }
+
     async getAdultVerificationRequests(req, res) {
         try {
             const { userid: requester } = req.headers;