K-Volatility Breakout

Raise bk_activation from 1.5% to 4.0%. The current 1.5% breakeven trigger is too sensitive, moving stops to breakeven too early and getting whipsawed out of profitable trades. A higher threshold allows more room for normal volatility, letting winners run while still protecting capital on strong moves. This improves Sharpe by increasing average win size and reducing premature stop-outs.