feat(pdf-split): add clear previews, per-page delete/restore, and zoo…

[pragya-manna]

🔀 Pull Request

📌 Issue Reference

Closes #270

📝 Summary

• Issue [Feature] : Add page preview with delete option in PDF Split feature #270 requested page preview and delete functionality for the PDF Split tool
• Added high-resolution page thumbnails (scale 1.5) with progressive loading — pages appear as they render instead of all at once
• Added per-page delete button (hover to reveal) that actually excludes deleted pages from the extracted PDF output
• Added restore button to undo any deleted page
• Added click-to-zoom modal for full-screen page preview
• Added "Selected" and "Removed" badges on thumbnail cards
• Range selection (start/end page) still works as before — delete works on top of it

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📸 Screenshots (if applicable)

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✅ Checklist

• My code follows the project's coding conventions
• I have tested all impacted features
• I have updated or added necessary documentation

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🔗 Related Issues / PRs

• Related to [Feature] : Add page preview with delete option in PDF Split feature #270
• Previous attempt: Add PDF page preview and delete feature #300

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🏅 Open Source Program Participation

Program Name: GSSoC

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💬 Additional Notes

Only PdfSplit.jsx was modified. No backend changes. All processing is client-side using pdf-lib and pdfjs-dist.

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[pragya-manna]

Thank you for merging this PR! I understand that documentation-only updates may not be a priority, but while working on the project I noticed that some parts of the README seem to be outdated after the recent changes. If you think it would be helpful, I'd be happy to open an issue and work on updating it to better reflect the current project structure and setup.