fix(site): load the top bar on the marketplace and 404 pages

[imran-siddique]

After #72, every agentrust-io.com page loads the shared top bar except two: /marketplace/ and the 404 page. A live check of the deployed site on 2026-09-14 found supernav.js on the homepage, community, verify, quickstart, demos, registry, go, telemetry and the cA2A extension page, and not on those two, so they showed the header without the bar above it.

This loads supernav.js on both, the same way the other pages do: a plain script tag before </body>.

/marketplace/catalog/ is left without it on purpose. It is the static catalog, and check-discovery.py requires that page to carry no script.

Checked

• build-header.py --check, check-site.py, check-discovery.py, build-discovery.py --check, check-dashes.js and marketplace.test.js pass.
• In headless Chrome against a local server, /marketplace/ and /404.html both render the bar with its nine links: agentrust-io, Verify, WCM, Manifest, cMCP, cA2A, TRACE, Governance, GitHub. GitHub Pages serves 404.html for unknown URLs; the local server does not, so the page was loaded by name.

Generated with Claude Code

https://claude.ai/code/session_013aK3gVWzNdcM3hZ2o2awK2