- Add matplotlib for chart generation
- Implement _calculate_heikin_ashi() for HA OHLC calculation
- Implement _generate_price_chart() to create candlestick + volume charts
- Charts are generated as PNG images and embedded in PDF
- Fallback to text summary if chart generation fails
- First page now shows visual charts like the web interface
- Page 1 now shows price statistics (growth rate, duration, start/end prices)
- Page 1 also includes last 5 trading days data
- Page 2+ contains the original analyst insights
- Updates pdf_generator.py, download_service.py, and routes.py