- charts.py: candlestick (mplfinance, dark theme) with EMA20/50
overlay, Bollinger Bands, RSI subplot and 30/70 reference lines
- /signal now sends chart image with analysis as caption
- New /chart <PAIR> <TF> command for standalone chart view
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>