Addresses Codex review feedback:
- Use series-based coordinate conversion (series.priceToCoordinate)
- Add infinite line extension math (_getInfiniteLineEndpoints)
- Fix message pattern: use sendToApp() not emit('message')
- Remove wall clock fallback in get_current_candle_time()
- Clarify architecture: socket handlers in BrighterTrades, not app.py
- Clarify UX: shape appears at center, drag to adjust (no click-to-place)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>