Open-rack / no-sides shelves span their boards across the full footprint, so a
board's end / front / back faces land exactly on the corner posts' outer faces
(and, with a back panel, on its rear face). Coplanar surfaces the depth buffer
can't order flicker as z-fighting (visible as seams where plates meet posts).
Recess every board 1mm on width + depth via a `boardGeometry` helper so each
plate sits just inside the frame — the meshes still overlap (no visible gap),
but no two faces are coplanar. Frame parts (posts/sides/back/dividers/brackets)
keep their full size as the silhouette.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
