Fractional sizing

Equity sizing floors to whole shares (II.8). For crypto that is wrong — a $250 risk on a $60k coin floors to 0 units. Crypto sizes in fractional units:

riskPerUnit = |entry − stop|
rawUnits    = (accountSize × riskFraction) / riskPerUnit
units       = floor(rawUnits / unitStep) × unitStep      unitStep = 1e-6 for crypto

The label is "units" (or the coin), not "shares." Equities keep unitStep = 1 (reproducing today's whole-share floor exactly). As with equities, size is a function of stop distance, not conviction. riskFraction 0.01 and exampleAccount 25000 (USD) are unchanged.