Seam W: InstanceSurfaceParams (whole_wet, lower_wet, waterline_y, feather) per rig
slot, a 2048-row table in the light buffer, applied in wow_model.wgsl through the
existing wet_surface/wet_sheen (max with rain wetness, opaque/alpha-test + fade
twins only). Zero row = stock image. Self-contained: cherry-pickable to lighting.
Seam F: WaterFoamSpawn message; plugin foam records live in their own 96-record
pool so they never evict or throttle the stock unit wake/ring records.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>