Implement approved-brief.md in this directory only. Keep it to the four
requested files plus the existing brief. No dependencies or network
requests. Treat the brief's scope as fixed. Use semantic HTML, real
buttons with aria-pressed, and a live result count for the filter.
After implementation, explain the files and report checks you actually
ran separately from checks I still need to perform in a browser.
Do not claim screenshots, accessibility tests or deployment happened
unless you actually performed them. Do not publish or push this project.