Updated sponsorship link and added Twicsy promotion.

Summary

Linked issue

Changes

Checklist

• Tests added or updated (or N/A with reason)
• Docs / types updated if public API changed (index.d.ts and index.d.cts)
• No breaking changes (or called out explicitly above)

Summary by cubic

Replaced the Open Collective sponsor link in the README with a Twicsy promo block (image, copy, and links) to reflect the current sponsorship and drive traffic via UTM links.

Description

• Summary of changes

  • Updated sponsorship link to Twicsy with UTM params.
  • Added Twicsy logo image, short description, and site link in the existing table cell.
  • Kept the layout and surrounding markup intact.

• Reasoning

  • Aligns the README’s sponsor section with the current sponsor and promotion.

• Additional context

  • Consider adding rel="noopener noreferrer" to external links that use target="_blank" for security.
  • Confirm the sponsor copy and branding meet project and community guidelines.

Docs

If the docs site mirrors the README sponsor section, update the corresponding content in /docs/ to include the Twicsy promo block and links.

Testing

No tests added. This is a README-only change. Manually verify:

• Links open correctly and include UTM params.
• Image loads and layout looks correct across light/dark modes.

Semantic version impact

No version impact. Docs-only change; no code or API modifications.

^{Written for commit e3c4f53. Summary will update on new commits.}