Bumps the kicad submodule to the threading revert (the 3D-viewer raytracer's
WASM single-threaded #ifdef fallbacks + the bs_thread_pool inline shim are gone;
those four files are now byte-identical to upstream KiCad).
Links wasm/shims/nanosleep_yield.c into every app (mirrors the gl_ffp_stub
pattern): the now-upstream raw-thread raytracer joins via a main-thread
sleep_for busy-wait, and this shim makes that nanosleep Asyncify-yield to the JS
event loop instead of deadlocking on on-demand pthread-Worker creation. Its
EM_ASYNC_JS yield is already covered by env.__asyncjs__* in asyncify-imports.txt.
This is what lets upstream's multi-threaded code run on WASM under native-EH.
Also documents isolated-worktree + submodule-branch creation in the README.
Result: ~11x faster 3D raytrace (21.3s -> 1.9s, 16 threads), pixel-correct
render, full kicad e2e green (63 passed / 0 failed).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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