Adds a `listing` fence to the rich-embed registry: JSON in, a native card
out — photo mosaic, address and price, specs, and the catches worth
verifying before a tour.
The rental portals publish no embeddable surface (public APIs deprecated or
broker-gated, no oEmbed, X-Frame-Options on every listing page), so a URL
cannot be framed. The data the agent already gathered can be, and the
portals' image CDNs hotlink fine — so the card is authored rather than
fetched, alongside the existing mermaid and svg fences.
Parsing treats every field as untrusted model output: one object, a bare
array, or `{listings: []}` all work, beds accept `3` and `"3.5"`, non-http
URLs are rejected so a card cannot smuggle a javascript: href, and lists
are capped. Anything unparseable falls back to the plain code block.
Brooklyn Nicholson
9b16719e17