`wipeout_boundary_2d` built the fill boundary from the wipeout's
insertion point cast straight to f32, stored in a HatchModel with
world_origin = [0, 0]. At UTM-scale coordinates (~1e6) f32 resolves to
~0.06, so the boundary collapsed and the relative-to-eye fill shader
cancelled `boundary - eye` to noise — the mask rendered as squares.
Return the boundary as small f32 offsets relative to a world_origin
(the insertion point, kept in f64) and set HatchModel.world_origin to
it at both the model-space and paper/viewport fill sites. Same fix as
the wide-polyline and on-create hatch fills.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
4e8521010b