- Add is_recommended field to Course model
- Add allow_multiple_attempts field to Quiz model
- Create RecommendedCoursesController for admin management
- List all approved courses
- Get course by ID
- Toggle recommendation status
- Add is_recommended filter to CoursesService.ListCourses
- Add allow_multiple_attempts to quiz update and response types
- Update ChaptersLessonService.updateQuiz to support allow_multiple_attempts
