Round-to-nearest 0.5% could land a nowrap flex row's width fractionally
below its intrinsic content width, wrapping it to two lines. When the
sizing probe shows a box painting at its max-content width with no slack,
the snap now ceils to the next step; all other boxes keep nearest
rounding, and the existing reproduce-verification still bails the plan on
any overshoot.
460 tests pass (2 new), typecheck clean.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>