Reads the file per request from USERSCRIPT_PATH and rewrites its @version
to an mtime-derived value, so Violentmonkey always sees a higher version
after an edit regardless of what the file body claims. Also guards against
ServeMux's own path-cleaning redirect turning an empty {token} segment into
a 307 instead of the required 404.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
