Fix Windows Chrome CDP spawn

[waml]

Summary

• Spawn Chrome/Edge/Brave directly for Chrome CDP without using a shell on Windows.
• Add a regression test proving Chrome CDP spawn options stay shell-free.
• Bump package to 0.2.4 and document the fix in the changelog.

Validation

• node --check chrome-cdp-backend.mjs
• npm test: 163/163 passing
• npm pack --dry-run --json: version 0.2.4, 40 files, no private/sprite workflow matches