- Change default backtest date range to 2026-03-02 through 2026-03-25
- Add spot_low and spot_high to BacktestDailyPoint for intraday range
- Update engine to populate low/high from DailyClosePoint
- Update daily results table to show Low, High, Close columns instead of just Spot
- Update job serialization to include spot_low and spot_high
- Extend DailyClosePoint to include low, high, open (optional)
- Update Databento source to extract OHLC data from ohlcv-1d schema
- Update YFinance source to extract Low, High, Open from history
- Modify backtest engine to use worst-case (low) price for margin call detection
This ensures margin calls are evaluated at the day's worst price,
not just the closing price, providing more realistic risk assessment.
