Add wasm32 Pyodide wheel support

[zardus]

Summary

• build PyVEX and its VEX submodule for a wasm32 Emscripten host
• run the generated-offset helper through the configured cross-compiling emulator
• select a 32-bit VEX host description for lifting-only browser use
• add PEP 783 Pyodide wheel configuration and CI

PyVEX does not emit host machine code in this use case; the selected host description supplies the host word size required by VEX lifting.

Validation

Built and imported the wheel under Pyodide 314.0.2. Tested AMD64 and ARM lifting, control-flow metadata, and 64-bit guest data references on wasm32.

[zardus]

Tandem PRs — please test these together:

• Support wasm32 hosts in VEX basic types vex#82
• Add wasm32 Pyodide wheel support #555
• Select the Pyodide Z3 build on Emscripten claripy#737
• Make native-only loaders optional on Emscripten cle#702
• Guard optional UEFI dispatch registration cle#703
• Test CLE under Pyodide cle#704
• Add Pyodide WebAssembly wheel support pypcode#283
• Add first-class WebAssembly runtime support angr#6658

[angr-bot]

Corpus decompilation diffs can be found at angr/dec-snapshots@master...angr/pyvex_555