Three bugs in discussArticle():
- Scroll selector was '.briefing-chat' (doesn't exist) → '.briefing-center';
the panel never scrolled into view so the response was invisible until refresh
- Only 300-char snippet was sent to the LLM; now passes the full stored
content (up to 2000 chars) from the backend
- User message wasn't shown until streaming ended; now added optimistically
to messages[] immediately on click so it appears straight away
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>