fix: improve visible focus styles

[web3blind]

Summary

• Add a dedicated focus ring color token for light and dark themes
• Add global :focus-visible styling with a 3px outline and offset for keyboard users
• Preserve high-contrast/forced-colors support with Highlight

Closes #1034

Checks

• npm run lint
• npm run type-check

Accessibility impact

Keyboard users get a visible focus indicator on buttons, links, and other focusable controls, including dashboard header controls in light mode.

[vercel]

@web3blind is attempting to deploy a commit to the PRIYANSHU DOSHI's projects Team on Vercel.

A member of the Team first needs to authorize it.

[github-actions]

GSSoC Label Checklist 🏷️

@Priyanshu-byte-coder — please apply the appropriate labels before merging:

Difficulty (pick one):

• level:beginner — 20 pts
• level:intermediate — 35 pts
• level:advanced — 55 pts
• level:critical — 80 pts

Quality (optional):

• quality:clean — ×1.2 multiplier
• quality:exceptional — ×1.5 multiplier

Validation (required to score):

• gssoc:approved — counts for points
• gssoc:invalid / gssoc:spam / gssoc:ai-slop — does not score

Type labels (type:*) are auto-detected from files and title. Review and adjust if needed.
Points formula: (difficulty × quality_multiplier) + type_bonus

[github-actions]

Thanks for your first PR on DevTrack! 🎉

A maintainer will review it within 48 hours. While you wait:

• Make sure CI is passing (type-check + lint)
• Double-check the PR description is filled out and the issue is linked
• Feel free to ask questions in Discussions if you need help

If you find DevTrack useful, a ⭐ star on the repo is always appreciated — it helps the project grow and attract more contributors!