⚡ Bolt: [performance improvement] O(log n) lookup for time-series data

[toreleon]

💡 What: Added findLastBarIndex binary search function and updated backtestRunner.ts and clipBars to use it.
🎯 Why: Replaces O(n) array .filter() inside the backtest loop over time-series data with an O(log n) binary search lookup. Prevents an O(n²) performance bottleneck when running backtests over large datasets.
📊 Impact: Exponential reduction in CPU cycles per backtest interval when querying historical bar data in sorted arrays.
🔬 Measurement: Verified with existing test suite via pnpm test and pnpm typecheck to ensure no functional regressions. Checked backtest timing.

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PR created automatically by Jules for task 11273309582741556229 started by @toreleon

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