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>

scripts/deps/build-cairo.sh

@@ -53,6 +53,12 @@ fi
 
 log_info "Building Cairo ${CAIRO_VERSION} for WASM..."
 
+# Always start meson fresh on a (re)build: meson caches its configuration, so a `meson setup` on an
+# existing build dir IGNORES a regenerated cross-file.txt — which silently dropped the EH/longjmp
+# flags (DEPS_EH_FLAGS) when switching JS-EH -> native-EH and left libcairo.a referencing
+# emscripten_longjmp. Wiping here (we only reach this past the stamp check, i.e. on a real rebuild)
+# forces meson to re-read the cross-file. Cairo is small, so the full reconfigure is cheap.
+rm -rf "${CAIRO_BUILD}"
 mkdir -p "${CAIRO_BUILD}"
 cd "${CAIRO_BUILD}"
 
@@ -65,6 +71,11 @@ else
     MESON_DEBUG_FLAGS="'-O2'"
 fi
 
+# Exception-model flags (DEPS_EH_FLAGS from env.sh) as meson list elements, e.g.
+# ", '-fwasm-exceptions', '-sSUPPORT_LONGJMP=wasm', '-sWASM_LEGACY_EXCEPTIONS=1'". Empty for legacy.
+MESON_EH_FLAGS=""
+for _ehf in ${DEPS_EH_FLAGS}; do MESON_EH_FLAGS="${MESON_EH_FLAGS}, '${_ehf}'"; done
+
 # Cairo uses meson
 cat > cross-file.txt << EOF
 [binaries]
@@ -94,8 +105,8 @@ b_pie = false
 # to prevent Cairo from defining its own conflicting implementations
 # Include ft2build.h and ftcolor.h to fix FT_Color forward declaration bug in cairo-ft-private.h
 # (the forward declaration is inside HAVE_FT_SVG_DOCUMENT but used in HAVE_FT_COLR_V1)
-c_args = [${MESON_DEBUG_FLAGS}, '-pthread', '-matomics', '-mbulk-memory', '-I${SYSROOT}/include', '-I${SYSROOT}/include/freetype2', '-I${SYSROOT}/include/pixman-1', '-DHAVE_CTIME_R=1', '-DHAVE_LOCALTIME_R=1', '-DHAVE_GMTIME_R=1', '-DHAVE_STRNDUP=1', '-include', 'ft2build.h', '-include', 'freetype/ftcolor.h']
-c_link_args = ['-pthread', '-L${SYSROOT}/lib']
+c_args = [${MESON_DEBUG_FLAGS}${MESON_EH_FLAGS}, '-pthread', '-matomics', '-mbulk-memory', '-I${SYSROOT}/include', '-I${SYSROOT}/include/freetype2', '-I${SYSROOT}/include/pixman-1', '-DHAVE_CTIME_R=1', '-DHAVE_LOCALTIME_R=1', '-DHAVE_GMTIME_R=1', '-DHAVE_STRNDUP=1', '-include', 'ft2build.h', '-include', 'freetype/ftcolor.h']
+c_link_args = ['-pthread'${MESON_EH_FLAGS}, '-L${SYSROOT}/lib']
 pkg_config_path = '${SYSROOT}/lib/pkgconfig'
 EOF
 

scripts/deps/build-freetype.sh

@@ -56,8 +56,8 @@ emcmake cmake "${FREETYPE_DIR}" \
     -DCMAKE_BUILD_TYPE=${BUILD_TYPE:-Debug} \
     -DCMAKE_INSTALL_PREFIX="${SYSROOT}" \
     -DCMAKE_POLICY_VERSION_MINIMUM=3.5 \
-    -DCMAKE_C_FLAGS="${DEBUG_CFLAGS:--g -O0} -pthread -matomics -mbulk-memory" \
-    -DCMAKE_CXX_FLAGS="${DEBUG_CFLAGS:--g -O0} -pthread -matomics -mbulk-memory" \
+    -DCMAKE_C_FLAGS="${DEBUG_CFLAGS:--g -O0} -pthread -matomics -mbulk-memory ${DEPS_EH_FLAGS}" \
+    -DCMAKE_CXX_FLAGS="${DEBUG_CFLAGS:--g -O0} -pthread -matomics -mbulk-memory ${DEPS_EH_FLAGS}" \
     -DFT_DISABLE_BZIP2=ON \
     -DFT_DISABLE_BROTLI=ON \
     -DFT_DISABLE_HARFBUZZ=ON \

scripts/deps/build-opencascade.sh

@@ -59,12 +59,27 @@ cd "${OCC_BUILD}"
 # OpenCASCADE build configuration for WASM
 # Disable GUI, visualization that needs X11/OpenGL native
 # Enable core geometry and data exchange modules only
+#
+# OCC's CMake unconditionally adds -DOCC_CONVERT_SIGNALS (occt_defs_flags.cmake), which turns the
+# OCC_CATCH_SIGNALS macro into setjmp(handler.Label()). The STEP read/write code
+# (STEPControl_Reader/ActorRead, ...) uses OCC_CATCH_SIGNALS pervasively. Under -fwasm-exceptions that
+# setjmp is lowered (emscripten's LowerEmscriptenEHSjLj) into a wasm-SjLj state-machine br_table whose
+# branch targets are inconsistently typed -> INVALID wasm that V8, wabt AND Binaryen all reject (this
+# is the "popping from empty stack" / br_table type-mismatch that blocks pcbnew's OCC link). WASM has
+# no POSIX signals, so OCC_CONVERT_SIGNALS (signal->exception conversion) is meaningless here anyway;
+# OCC's normal C++ Standard_Failure throw/catch is unaffected. Disabling it means OCC_CATCH_SIGNALS
+# expands to nothing (clang) -> no setjmp -> no wasm-SjLj -> valid native-EH wasm.
+_occ_defs="${OCC_DIR}/adm/cmake/occt_defs_flags.cmake"
+if grep -q '^[[:space:]]*add_definitions(-DOCC_CONVERT_SIGNALS)' "${_occ_defs}" 2>/dev/null; then
+  sed -i 's|add_definitions(-DOCC_CONVERT_SIGNALS)|# add_definitions(-DOCC_CONVERT_SIGNALS) # disabled for native wasm-EH by build-opencascade.sh (no POSIX signals in WASM; setjmp breaks -fwasm-exceptions)|' "${_occ_defs}"
+  log_info "Disabled OCC_CONVERT_SIGNALS for native wasm-EH (avoids invalid wasm-SjLj br_table)"
+fi
 emcmake cmake "${OCC_DIR}" \
     -DCMAKE_POLICY_VERSION_MINIMUM=3.5 \
     -DCMAKE_BUILD_TYPE=${BUILD_TYPE:-Debug} \
     -DCMAKE_INSTALL_PREFIX="${SYSROOT}" \
-    -DCMAKE_CXX_FLAGS="${DEBUG_CFLAGS:--g -O0} -pthread -matomics -mbulk-memory" \
-    -DCMAKE_C_FLAGS="${DEBUG_CFLAGS:--g -O0} -pthread -matomics -mbulk-memory" \
+    -DCMAKE_CXX_FLAGS="${DEBUG_CFLAGS:--g -O0} -pthread -matomics -mbulk-memory ${DEPS_EH_FLAGS}" \
+    -DCMAKE_C_FLAGS="${DEBUG_CFLAGS:--g -O0} -pthread -matomics -mbulk-memory ${DEPS_EH_FLAGS}" \
     -DBUILD_LIBRARY_TYPE=Static \
     -DBUILD_MODULE_ApplicationFramework=OFF \
     -DBUILD_MODULE_Draw=OFF \