[amesk]

Summary

• Add a floating, localized Back to Top button to both the landing-page Overview and User Manual.
• Show it only after the reader scrolls down, keeping the initial view uncluttered.
• Use one shared component and mount it only for the Overview and Manual views (not the emulator or Devlog).
• Respect prefers-reduced-motion; retain keyboard focus styling and accessible labels.
• Keep the button 8 px from the bottom edge on all screen sizes.

Implementation

The scroll behaviour lives in ManualBackToTop; App.tsx owns the single shared instance so it appears on the two long-form views without duplicates. The existing end-of-manual link remains unchanged.

Verification

• Reviewed the current component and app-shell integration on the PR branch.
• GitHub currently reports the PR as mergeable.
• Automated build/tests have not been run in this environment.