Render interactive catalog resources in an in-app HTML viewer

[soyalejolopez]

Summary

Interactive catalog resources now render their HTML page inside the app instead of only linking out to GitHub.

The two interactive resources — Copilot Agents Guide and Agents Cost Calculator — get a new "View" button on their detail card. Clicking it opens the rendered page in a modal (window-inside-a-window) with a header that includes an "Open in new tab" link and a close control.

What changed

• New "View" button on the detail view for interactive resources; View becomes the primary action and Open on GitHub moves to secondary.
• In-app viewer modal with header (resource name, "Open in new tab ↗", close ✕) and an iframe rendering the local index.html.
• Embed path is derived from each resource's source (README.md -> index.html), so no catalog.json schema changes are required.
• Closes via ✕, backdrop click, or Esc; iframe resets and page scroll unlocks on close.
• Vanilla JS + existing CSS variables, so it's automatically correct in light/dark themes.

Testing

Served the site locally and verified: card -> View opens the modal, the iframe renders the live tool, the "Open in new tab" link resolves to the correct page, and Esc/backdrop/✕ all close cleanly. Only index.html is modified.