test: fix npm stub on Windows

[angeloashmore]

Resolves:

Description

Windows CI times out on the init and gen setup tests almost every run.

Reason: The npm stub in test/it.ts never worked on Windows: it is a POSIX shell script with a shebang (Windows only executes .exe/.cmd/.bat), and the stub directory was prepended to PATH with : instead of ;. Tests therefore ran the real npm install next@latest in a temp dir, which takes 30–180s on Windows runners and blows the 30s test timeout.

Solution: Add an npm.cmd stub next to the existing sh stub and use path.delimiter for the PATH prepend.

Checklist

• A comprehensive Linear ticket, providing sufficient context and details to facilitate the review of the PR, is linked to the PR.
• If my changes require tests, I added them.
• If my changes affect backward compatibility, it has been discussed.
• If my changes require an update to the CONTRIBUTING.md guide, I updated it.

Preview

How to QA ¹

Check that the test windows jobs pass without the init/gen setup timeouts.

🤖 Generated with Claude Code

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