web: point footer build-SHA link at benchmarks-website, not the monorepo

The footer SHA is VERCEL_GIT_COMMIT_SHA — this repo's deploy commit — so the
commit link must resolve in vortex-data/benchmarks-website, not vortex-data/vortex
(where that SHA does not exist). Per-datapoint chart commit links are unchanged:
those are Vortex-library commits and correctly point at the monorepo.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: connortsui20

web/components/Footer.tsx

@@ -14,7 +14,7 @@
 export function Footer() {
   const fullSha = process.env.VERCEL_GIT_COMMIT_SHA ?? 'unknown';
   const shortSha = fullSha.slice(0, 7);
-  const commitUrl = `https://github.com/vortex-data/vortex/commit/${fullSha}`;
+  const commitUrl = `https://github.com/vortex-data/benchmarks-website/commit/${fullSha}`;
   return (
     <footer className="site-footer">
       <span className="site-footer-label">build </span>