[transfix]

publish-pycvc-gl-wasm failed on the v3.7.1 and v3.7.2 tag runs (40467963385, 40770763052), so no pycvc-gl-cp312 wasm package exists for either version. The catalog's newest is 3.7.0+cvc.1. Fixing that first failure exposed a second one: the host it builds is invalid wasm. This PR fixes both.

1. The configure found no ImageMagick

pycvc-gl(wasm): FATAL — the configure found no ImageMagick in /home/runner/work/libcvc/libcvc/wasm-deps

#801 made imagemagick a wasm build dep of pycvc-gl-cp312 and made build-wasm.sh fail without it. The workflow, though, installs a list of deps typed out by hand, and that list never gained imagemagick. #801 did not run the pycvc-gl wasm build, and nothing ran this workflow between #801 and the v3.7.1 tag. The prefix itself was fine: Boost, Assimp, libjpeg-turbo and ImGui were all found. The other "not found" lines (libigl/Eigen, Jolt, yaml-cpp, FTXUI, json-schema-validator, SDL3) are outside this recipe's wasm closure; v3.7.0's green publish (39395829831) reports the same ones.

• The install step runs cvcpkg install-deps cvcpkg/recipes/pycvc-gl-cp312 --platform wasm --arch wasm32 …, so it installs whatever the recipe declares and cannot drift from it again. freetype, assimp and imgui, which the closure links but the recipe does not declare, are still installed by name.
• The step sets pipefail. Under the default bash -e, cvcpkg install … | tail -3 || error took its status from tail, so a failed install passed.

2. The host did not compile

With ImageMagick in, dry run 40785015722 built, packed and went green. But its pycvc_host.wasm fails under node:

CompileError: WebAssembly.instantiate(): Compiling function #285254 failed: expected 0 elements on the stack for fallthru, found 1

• link-host.sh links every $DEPS/lib/*.a in one group under --allow-multiple-definition.
• VTK's bundled libxml2 (libvtklibxml2-9.5.a) mangles only libxml2's public API (vtklibxml2_xml*). 65 internals keep their plain names: __xmlRaiseError, __xmlIOErr, xmlBuf*, xmlDict* and more.
• ImageMagick now pulls cvcpkg's libxml2 2.12.9 into the link. Its references to those internals resolve to VTK's copy, which sorts first, and then both copies link.
• wasm-ld warns function signature mismatch for __xmlRaiseError, __xmlIOErr and xmlBufAttrSerializeTxtContent. VTK's newer __xmlRaiseError returns int, and 2.12's caller leaves that value on the stack. The invalid function is that caller: it checks XML_SAX2_MAGIC (0xDEEDBEAF) and calls a 17-argument function returning i32.
• v3.7.0's host has no libxml2 code at all.

Reproduced on its own with emsdk 5.0.7 and the catalog archives: a 12-line libxml2 program linked the same way gives the same three warnings and the same CompileError. Without libvtklibxml2 in the group, libxml2.a links with no undefined symbols (ERROR_ON_UNDEFINED_SYMBOLS=1) and parses correctly.

• link-host.sh leaves libvtklibxml2-*.a out of the group. VTK's copy has one user, vtkXMLTreeReader, which the vtk-python build does not reference. If one is added, the log will show vtklibxml2_* as undefined symbols.
• link-host.sh's node smoke is non-fatal, so the broken host shipped in a green build. The verify step now runs a bundled host under node and fails without PYCVC_VTK_BRIDGE_OK and PYCVC_WASM_OK. Checked locally against the two hosts: v3.7.0's passes, 40785015722's fails.

Proof

Dry run on 77772ca: 40795092841 (dry_run=true, so nothing is published) passed:

• configure: ImageMagick found: …/include/ImageMagick-7 (Q16, HDRI=1);
• host link: no libxml2 signature mismatches, and no undefined vtklibxml2_*. Only numpy's random_* warnings remain, which v3.7.0's working link had too;
• the host runs under node, and both link-host.sh's smoke and the new verify gate print PYCVC_VTK_BRIDGE_OK and PYCVC_WASM_OK;
• bundle: pycvc-gl-cp312-3.7.2+cvc.1-wasm-wasm32-release-static.tar.gz (85.8 MB), carrying only its own manifest.

After merge

Dispatch publish-pycvc-gl-wasm on master with dry_run=false to publish pycvc-gl-cp312 3.7.2+cvc.1 for wasm. This build compiles cvc from source, so the package will also carry master's #851 (cvc::ph steering modulation, opt-in) and #858 (CI only), which are past the v3.7.2 tag.