Re-vendors wide 0.7 + safe_arch, restores the upstream simd-stable
wiring in rapier3d/parry3d manifests and the cfg-simd source, and drops
the added 'stripped build does not support SIMD' guards (upstream's
simd-vs-enhanced-determinism exclusivity guard kept).
Interleaved single-thread retest (min of 4): SIMD buys rapier 1.8-2.2x;
box3d vs rapier-simd is now near parity — large_pyramid 1579 vs 1638 ms,
joint_grid 957 vs 1008 ms (box3d ahead), many_pyramids 2389 vs 1970 ms
(rapier ahead). box3d README grid updated with the honest three-column
table; box3d keeps cross-arch determinism + zero deps at that speed.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Same scenes/geometry/materials/dt, matched solver budget (4 substeps vs
4 solver iterations), interleaved min-of-4 runs: large_pyramid 2.23x,
many_pyramids 1.82x, joint_grid 1.88x (geomean ~1.97x). Table + fairness
notes at the top of the box3d README (vendored rapier has no SIMD;
enhanced-determinism measured free on these scenes).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
