PUSHPAK-JAISWAL/OSS-Proof ? reverse-engineered prompt

Build me a GitHub Pages app that lets open source developers get a contribution certificate and badge for their profile README.

I want users to be able to paste in a GitHub username, see a score based on their merged pull requests in repos they do not own, and then request a certificate through a GitHub issue. The app should show the certificate on a public page, let people verify it in the browser, and give them markdown and HTML they can copy for a badge card and a small badge.

It should work without a database or server, just store files in the repo and read public GitHub data in the browser. Please make it feel polished and trustworthy, with clear score breakdowns, a list of counted pull requests, and a simple way to verify the signature. If you need current GitHub or Pages details, look them up online first.