feat: shareable public profile page /u/[username] with opt-in public stats (#2117)

[IshitaSingh0822]

Summary

Implements the shareable public profile page at /u/[username] with opt-in public stats as described in #2117.

Closes #2117

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Type of Change

• Bug fix
• New feature
• Documentation update
• Refactor / code cleanup

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Changes Made

• Added public_widgets jsonb column migration with default ["streak", "contributions"]
• Updated settings API route to handle public_widgets in GET and PATCH with graceful tier fallback
• Updated public-profile-data.ts to expose PublicWidgetKey type, memberSince, and publicWidgets fields
• Updated public profile page to show GitHub avatar, member-since date, View on GitHub link, language breakdown, PR count, and Powered by DevTrack footer badge
• Updated settings page to add widget selector checkboxes inside the Public Profile card

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How to Test

1. Enable Public Profile in /dashboard/settings
2. Select which widgets to show using the new checkboxes and click Save
3. Visit /u/[your-github-username] and verify only selected widgets appear
4. Disable public profile and visit the same URL and verify 404 page appears
5. Call GET /api/public/[username] without auth and verify it returns stats

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Screenshots (if UI change)

N/A

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Checklist

• Linked issue in summary
• npm run lint passes locally
• No TypeScript errors (npm run type-check)
• Self-reviewed the diff
• Added/updated tests if applicable

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Accessibility Checklist

• Proper keyboard navigation tested
• Responsive UI verified
• Accessibility labels added where needed

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Additional Notes

The public_widgets column falls back gracefully if the migration has not been run yet so no breaking changes for existing deployments.

[vercel]

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[github-actions]

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