agents/llm.md promises "play the Nth video from the top", but browseAndPlay
only ever clicked the first result. Add an optional 1-based index argument
(default 1, backward-compatible) threaded to the Node helper, which now clicks
the Nth a#video-title and clamps to the number of results returned so asking
beyond the list plays the last available video instead of failing.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
