Record OSWEC published-step nonlinear motion gap

[cmccomb]

What changed

Record the direct independent Python comparison against the untouched published 0.1 s OSWEC nonlinear visualization run, alongside MATLAB's own 0.1-to-0.0125 s change. The case remains qualified; no badge count changes.

Evidence

• Source runs 38259283403 and 38325882473 use pinned WEC-Sim and Applications revisions. PR Gate OSWEC refinement against published motion #275 gates the refined run's coarse output against the published output exactly.
• With the pinned HDF5 and flap mesh, the same Python run differs from the published source by 0.007301 rad pitch, 0.005409 rad/s pitch speed, and 33.66 mm surge over 120 s. MATLAB's own published-to-refined changes are 0.007192 rad, 0.005308 rad/s, and 33.16 mm.
• The refined-step independent motion gates remain unchanged. git diff --check passed.