feat(vocab): implement user vocab lesson progress reset functionality

- Added `resetUserVocabLessonProgress` method in `AdminController` to allow admins to reset a user's progress for a specific vocab lesson.
- Introduced corresponding route in `adminRouter` for the new reset functionality.
- Enhanced `VocabService` with methods to purge lesson progress for users, ensuring that only the specified lesson's progress is affected.
- Updated UI components in `UsersView` to facilitate the selection of courses and lessons for resetting progress, including confirmation dialogs and loading states.
- Added localization support for the new reset functionality across multiple languages.
- Implemented reset functionality in `VocabLessonView` for users to reset their own lesson progress.

frontend/src/i18n/locales/en/socialnetwork.json

@@ -487,6 +487,10 @@
                 "score": "Score",
                 "review": "Review",
                 "start": "Start",
+                "resetLessonProgress": "Reset lesson",
+                "resetLessonProgressConfirm": "Reset progress for this lesson? Saved state, exercise results, and trainer progress will be cleared. Other lessons stay unchanged.",
+                "resetLessonProgressSuccess": "Lesson progress was reset.",
+                "resetLessonProgressError": "Could not reset the lesson.",
                 "noLessons": "This course has no lessons yet.",
                 "lessonNumber": "Lesson Number",
                 "chapter": "Chapter",