content: add GatedSRP and sparse autoencoder publications

[chengjiahao1234]

Type of Change

• Content Update (news, publications, team)

Summary

Add GatedSRP and Beyond the Hard Budget, and announce GatedSRP's BMVC 2026 oral acceptance.

Changes Made

• _data/publications.yml: add both papers with authors, metadata, and arXiv/DOI links; include GatedSRP's project and code links.
• _data/news.yml: add the BMVC oral acceptance announcement.
• images/pubpic/: add original publication thumbnails.

Testing Checklist

• Desktop (1920x1080), tablet (768x1024), and mobile (375x667)
• Light and dark themes
• New links verified; no broken images on tested pages
• No console errors or horizontal overflow
• Ran bundle exec jekyll serve successfully
• YAML validation and git diff --check

Additional Notes

• News date follows BMVC's presentation-format notification schedule, not a paper-specific acceptance email.
• Beyond the Hard Budget follows the existing preprint listing convention; no unverified code or Hugging Face links were added.
• Screenshots captured locally; not attached. No related issue.

By submitting this PR, I confirm:

• Tested locally and followed DEVELOPMENT.md
• Documentation changes are unnecessary for this content-only update
• Ready for review