fix(release): complete package smoke recovery

[fullzer4]

Summary

• update Maturin so Python sdists contain a valid virtual workspace
• invoke npm through the Windows shell and surface spawn errors
• load the native Node addon in a child process so Windows can clean up the package tree

Validation

• actionlint
• exact stdbr-0.3.3.tar.gz build, install, runtime, and mypy smoke
• exact Node package smoke on Linux
• full cross-platform package smoke run 34302056450, including Python sdist and Node/FFI Windows