react-progress-bar.js (unmaintained wrapper) rendered the progress line
through findDOMNode. Reimplemented LoadingBar with progressbar.js directly
(the wrapper's own underlying dep) via a ref + useEffect — same thin line
(strokeWidth 2, #5A7636), no findDOMNode. Promoted progressbar.js to a
direct dependency and removed react-progress-bar.js. Verified progressbar.js
draws its SVG in-browser; findDOMNode gone from /fires and home; REST smoke
byte-identical.