markdown-it linkify: true has two quadratic paths, so a few hundred KB of markdown blocks the event loop for tens of seconds

Summary Two independent quadratic paths in the linkify: true handling. Both are in markdown-it's own code rather than in linkify-it, which stays linear on both payloads. src/rulescore/linkify.ts calls arrayReplaceAt once per linkified text token, and that rebuilds the whole children array each...