- Add option_contracts field to BacktestDailyPoint (number of contracts held)
- Update engine to calculate total option contracts from positions
- Update job serialization to include underlying_value, option_market_value, net_portfolio_value, option_contracts
- Update both render_result and render_job_result tables to show:
- Low, High, Close (from previous commit)
- Portfolio value (net_portfolio_value)
- Option value (option_market_value)
- Contracts (option_contracts)
- LTV hedged
- Margin call status