fix(docs): reveal active ecosystem link synchronously

[EmersonBraun]

Summary

• reveal the active mobile product without relying on requestAnimationFrame
• support background tabs and delayed rendering consistently
• add a regression assertion against deferred scrolling

Validation

• focused Vitest passed
• full repository pre-push quality gates and build passed

[github-actions]

Lighthouse

URL	Performance	Accessibility	Best practices	SEO
http://127.0.0.1:3000/	43	92	96	100
http://127.0.0.1:3000/docs	72	100	96	100
http://127.0.0.1:3000/docs/get-started/getting-started/quickstart	69	96	96	100
http://127.0.0.1:3000/stack	94	100	96	100
http://127.0.0.1:3000/showcase	92	100	96	100

Run by .github/workflows/lighthouse.yml.