fix: cache yfinance misses, pass pre-fetched caps to all plot sims
- _fetch_market_caps: parallel fetch (20 threads), skip tickers with '/',
cache None results so missing tickers are never re-queried
- simulate: fix prices.get() default from {} to ([], []) for bisect compat
- plot_position_size: pass _signals/_market_caps to avoid per-sim refetch
- plot_equity_curves: use tuple-based SPY price access
- plots: regenerate all three (hp_sweep, equity_curves, position_size)
- README: add position_size.png embed
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Dominik Roth
9417a9e542