Bodies were printed verbatim, so an agent's **bold**, `code`, or
[link](https://...) showed as literal punctuation — the opposite of
people talking. Render the inline markdown agents and humans actually
use in chat into React nodes, composed around the existing @mention
highlighting.
Links are restricted to http(s) and nothing is ever set as raw HTML
(no dangerouslySetInnerHTML), so a message body can never inject markup
or a javascript: URL. A plain message still comes back as one string.