- Add /api/pnl/history endpoint to app.py for daily P&L history charting
- Rewrite index.html as full SPA with Chart.js bar chart, summary cards,
and decisions log table with market filter tabs and 30s auto-refresh
- Add test_pnl_history_all_markets and test_pnl_history_market_filter tests
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>