Exam widget: Alternate question set for retakes enables task-level feedback

If a user does not pass the exam on the first attempt, the retake could be generated from an alternate question set. This reduces the likelihood of memorizing answers and helps ensure the exam measures broader, real competence.

Using a different question set also enables showing task-level feedback after the first attempt. If the retake does not reuse the same questions, we can safely provide per-question explanations or feedback without giving away answers for the next attempt. This supports learning and helps users identify which topics they need to improve before retaking the exam.