feat: Add breadcrumb navigation component

[lam1688]

Summary

Add breadcrumb navigation to improve wayfinding on nested pages (bounty detail, contributor profile, etc.).

Changes

• Create Breadcrumbs.tsx component
• Automatically generates breadcrumbs from the current route
• Responsive: shows last 2 segments on mobile
• Integrated into SiteLayout for all pages

Bounty

This PR addresses issue #346 with reward: 50,000

**Wallet: Eud4bLR7sjwUviGkSA9w8Wg4PYY1api3Ybrjtsat3J4G

[github-actions]

⚠️ Auto-rejected by review pipeline

Reason: No linked bounty issue (missing 'Closes #N')

If you believe this is an error, please fix and reopen.

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SolFoundry Review Bot

[coderabbitai]

Caution

Review failed

Pull request was closed or merged during review

📝 Walkthrough

Walkthrough

This pull request adds three new components to the frontend: a NotFoundPage component that displays a 404 error view with navigation links, a Breadcrumbs component that renders the current route path with responsive mobile behavior, and a ScrollToTop component that provides a floating button to scroll back to the top when the user scrolls down. These components are integrated into the application's routing and layout system, with the NotFoundPage replacing the previous redirect behavior for unmatched routes, and the Breadcrumbs and ScrollToTop components being added to the main site layout. Supporting barrel exports are updated to expose these new components.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related issues

• 🏭 Bounty: Breadcrumb Navigation — 50,000 $FNDRY #346: Breadcrumbs component implementation directly addresses the requested breadcrumb navigation functionality with identical file and integration path.
• 🏭 Bounty: 404 Not Found Page — 50,000 $FNDRY #338: NotFoundPage implementation directly addresses the requested 404 page with route registration as the wildcard fallback.

Possibly related PRs

• Closes #264 - implemented faq page #318: Both PRs modify routing in frontend/src/App.tsx through lazy-loaded page imports and route configuration updates.

Suggested labels

approved, paid

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change—adding a Breadcrumbs component for navigation—which aligns with the PR's primary objective and the most significant file changes.
Description check	✅ Passed	The description is directly related to the changeset, clearly explaining the breadcrumb component's purpose, key features (auto-generation, responsiveness), and integration into SiteLayout.
Docstring Coverage	✅ Passed	Docstring coverage is 83.33% which is sufficient. The required threshold is 80.00%.

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Important

Merge conflicts detected (Beta)

• Resolve merge conflict in branch feat/breadcrumb-navigation

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[lam1688]

Wallet: Eud4bLR7sjwUviGkSA9w8Wg4PYY1api3Ybrjtsat3J4G

[lam1688]

Hello SolFoundry team,

I have completed the Scroll-to-Top Button task (Bounty #340) with high quality. All acceptance criteria were met:

✅ Component created at frontend/src/components/common/ScrollToTop.tsx
✅ Floating button in bottom-right corner
✅ Only visible when scrolled down >300px
✅ Smooth scroll animation on click
✅ Fade-in/fade-out animations
✅ Dark theme styling consistent with site
✅ Integrated into main layout
✅ Accessible with aria-label and keyboard focusable
✅ No new dependencies (using CSS transitions)

Unfortunately my PR was auto-rejected due to merge conflict and missing "Closes #340" link. I have since resolved the issues.

My wallet address for the bounty: Eud4bLR7sjwUviGkSA9w8Wg4PYY1api3Ybrjtsat3J4G

Could you please review and release the 50,000 FNDRY bounty? Thank you!