OG image per project page #24

Why

A project link shared in Discord or X should show a card, not a blank preview.

In this repo today

The web app is a client rendered SPA on Vercel, and crawlers do not run JavaScript, so meta tags cannot be set in React. The card needs a server side step.

What to build

• A Vercel function under apps/web/api/ that renders a PNG with satori and resvg from /api/projects/{id}: name, tagline, contracts count, evidence tier and the hackathon name.
• A rewrite in vercel.json that sends /project/* requests from known link preview crawlers to a function returning HTML with the right og:title, og:description and og:image. A default card for the home page uses the timeline chart.

Acceptance criteria

• Sharing a project URL in Discord shows the card.
• Normal visitors still get the SPA.

See CONTRIBUTING.md for conventions.