KaTeX (BSD-licensed) must be placed here at build time for offline live re-render:
  curl -L https://github.com/KaTeX/KaTeX/releases/latest/download/katex.tar.gz | tar xz
  cp katex/katex.min.js katex/katex.min.css here (+ fonts/).
Not committed (size); the review bundle degrades to plain LaTeX text if absent.
