Introduces a BacktestClient that replays historical 1-min bars against the
existing strategy code, plus a CLI entry point (npm run backtest) that fetches
bars from Alpaca and runs the bot over a date range. Makes wait() pluggable
so the backtest resolves delays instantly while advancing simulated time.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
