feat(wasm-eh): migrate the WASM build to native wasm exceptions (+ 3D viewer default-on)

Replace the legacy Emscripten JS-exceptions model with native wasm-EH (legacy
encoding) across the whole build, keeping Asyncify coroutines working via a
from-source Binaryen --hoist-cpp-catches pre-pass. Net result: native-EH is the
only build mode, the 3D viewer is on by default, and pcbnew shrinks substantially.

Highlights:
- Binaryen submodule everywhere + --hoist-cpp-catches integration in apply-asyncify;
  post-link Asyncify covers every app wasm (not just standalone test wasm).
- Build deps (incl. OpenCASCADE without OCC_CONVERT_SIGNALS) and all KiCad apps
  with -fwasm-exceptions; emscripten_sleep added to the post-link asyncify-imports.
- libcontext fiber entry wired under native exceptions; while-loop main loop +
  currData shim injected into all wx apps.
- Native-EH collab apply fixed: DEBUG-define the embind TU + match all out-of-CMake
  C++ TUs' ABI flags to the core, fixing the vtable-layout skew / mis-dispatch.
- 3D viewer enabled by default (real raytracer linked, not the stub).
- Retire the EH-spike scaffolding; flip the asyncify-races ablation pins to
  shim-redundancy pins (native-EH stays clean with the legacy shims ablated).
- Fix the asyncify-races quiescence check to not require Asyncify.currData==0:
  under the native-EH per-frame-yield top loop the main stack is asyncify-suspended
  every frame, so currData legitimately churns (a freed-but-not-yet-nulled buffer,
  not a leak). Refresh the pcbnew toolbar screenshot baseline for the new kicad.
- CI: drop the obsolete binaryen_version input/env (the build uses the binaryen
  submodule fork's wasm-opt, not a version download); key the wasm-output cache on
  the binaryen submodule SHA instead.

Bumps the wxwidgets + binaryen submodules to their squashed feature commits.

Validated green: all 7 apps native-EH (real 3D in pcbnew); KiCad e2e 63/63
Firefox + Chromium (3D viewer renders); wx 336; coroutine 34/34 both engines;
asyncify 7/7 both engines.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/apps/standalone/asyncify-races/races_test.cpp

@@ -163,17 +163,29 @@ EM_JS( void, races_mark_done, ( const char* aName ), {
     Module.__racesDone[UTF8ToString( aName )] = true;
 } );
 
-// Quiescence invariant sampled from C++ between scenarios. NOTE: this runs on a
-// stack that may itself have been resumed via Fibers.trampoline(), in which case
-// Fibers.trampolineRunning is legitimately true — so the guard is deliberately
-// NOT part of this check (a genuinely stuck guard wedges the next fiber swap and
-// is caught by the scenario watchdogs instead).
+// Quiescence invariant sampled from C++ between scenarios.
+//
+// Two things are deliberately NOT checked:
+//   * Fibers.trampolineRunning — this can run on a stack itself resumed via
+//     Fibers.trampoline(), in which case the guard is legitimately true.
+//   * Asyncify.currData — under native wasm-EH the top-level event loop is a
+//     per-frame-yield while-loop (wxWasmYieldToBrowser, an EM_ASYNC_JS rAF
+//     suspend that re-arms every frame; see wxwidgets/src/wasm/evtloop.cpp). So
+//     the main stack is asyncify-suspended between frames and currData is
+//     legitimately churning — it is non-zero while a frame yield is pending, and
+//     can momentarily hold a freed-but-not-yet-nulled buffer right after a
+//     concurrent suspension resumes. That is a transient bookkeeping value, NOT a
+//     leak (the buffers are _malloc/_free'd each frame — addresses are reused),
+//     so requiring currData==0 here is a stale legacy assumption from the old
+//     throw-to-park loop. A genuinely stuck suspension is caught by state != 0
+//     (Suspending/Rewinding never clearing) and by the scenario watchdogs.
+// What's left is the real invariant: the asyncify machine is back to Normal and
+// no fiber is queued.
 EM_JS( int, races_quiescent, (), {
     try {
         var stOk = ( typeof Asyncify === 'undefined' ) || Asyncify.state === 0;
-        var cdOk = ( typeof Asyncify === 'undefined' ) || !Asyncify.currData;
         var nfOk = ( typeof Fibers === 'undefined' ) || !Fibers.nextFiber;
-        return ( stOk && cdOk && nfOk ) ? 1 : 0;
+        return ( stOk && nfOk ) ? 1 : 0;
     } catch( e ) {
         return 0;
     }