fix: add image resoures cleaner

[shinyu0430]

Problem

When users upload images and subsequently remove the corresponding markdown syntax, the system continues to include these unused image files in exported packages.

Solution

Remove unused image files before export

• Parse generated HTML content:
  • STEP1: convert HTML string to DOM object
  • STEP2: identify <img> tags by extracting data-id attributes
  • STEP3: matching them against the image resource list.
• Fallback mechanism: Utilize markdown text analysis when HTML parsing encounters errors

I should have commented rather than approved.

[shinyu0430]

@WendellLiu I've updated it. Please let me know if it’s ok to merge 🙏🏻

[WendellLiu]

@shinyu0430 Thank you. It's good to merge.