feat: fix majority bugs in create bugs excel

[fanxiaotuGod]

Summary

This PR fixes multiple question-generation, review/edit, export, and H5P compatibility issues across the CREATE workflow.

Fixed Bugs and Improvements

• Restored and improved Back to AI Plan Configuration so users can return to the plan page after generation.
• Added safer regeneration behavior: when questions already exist, users can choose to add new questions or replace existing questions.
• Moved the back-to-plan action higher in the UI so users no longer need to scroll to the bottom.
• Fixed repetitive MCQ generation by improving LO slicing and question planning, so repeated questions are less likely and broad LOs are split more intelligently.
• Added MCQ answer modes: single-answer and multiple-answer.
• Added MCQ per-option fields for:
  • tip
  • feedback if selected
  • feedback if not selected
• Fixed H5P MCQ export so option-level tips/feedback and multiple-correct-answer behavior are preserved.
• Added Markdown export support.
• Improved PDF/Markdown answer exports to include:
  • explanations
  • tips
  • answer feedback
  • multiple correct answers
• Fixed AI Generate in Review & Edit -> Add new question by wiring it to the generation flow.
• Fixed LO labels showing raw IDs in some plan dropdowns.
• Improved Review/Edit field labels so tip, feedback if selected, and feedback if not selected are clearly distinguished.
• Fixed Single Choice Set issues in interact mode:
  • disabled unwanted auto-advance behavior
  • fixed broken Retry / Show solution behavior caused by H5P solution view initialization
• Fixed Delivery Target / H5P Package Format selection not updating correctly in Generate Questions.
• Unified user-facing naming by changing Cloze to Fill in the Blank.
• Synced Review & Edit -> Add question question types with the currently selected delivery target / format.
• Added compatibility checks when switching delivery target / format:
  • incompatible existing questions now trigger a warning and removal confirmation
  • incompatible plan items now trigger a warning before being converted to supported types

UX Improvements

• Question-type availability is now consistent between Generate Questions and Review & Edit.
• Format/target changes are safer and more transparent when existing questions or plan items are incompatible.
• Review/Edit forms now better reflect H5P answer feedback behavior for MCQs.

Notes

• Existing H5P and export flows were updated to better support richer MCQ metadata and answer-mode behavior.
• Several fixes also improve alignment between plan configuration, generated questions, and exported output.