fix: use execFile to bypass shell command resolution-W-23662030

[soridalac]

Summary

• Replace child_process.exec() with child_process.execFile() when invoking npm
• execFile does not spawn a shell, preventing unintended command resolution from the working directory on Windows

Test plan

• Existing unit tests pass
• Verified sf version --verbose works correctly on Windows and macOS
• Verified npm registry lookup still returns version info for user-installed plugins

@W-23662030@

[git2gus]

Git2Gus App is installed but the .git2gus/config.json doesn't have right values. You should add the required configuration.