fit_wf_ms_sizes (pure, unit-tested) passes the fixed 90/30/30-day roller
through byte-identically whenever it fits the resolved campaign window,
and scales it down preserving the 3:1 IS:OOS ratio (step = OOS, one roll
at the minimum) when the window is shorter — so mc/walkforward --real
over a ~30-day window run to completion instead of dead-ending at the
executor with a remedy unreachable from the verb surface. Both dispatch
sites consume the fit; the executor's own check stays for authored
process documents. Verb help documents the fit.
closes#239
Brummel
2a63c5d889