Function run_script 

pub async fn run_script(
    script_dir: &Path,
    project_root: &Path,
    modules_dir_name: &str,
    manifest: &PackageJson,
    script_name: &str,
    script_cmd: &str,
) -> Result<(), Error>

Run a single npm-style script line through sh -c with the usual environment ($PATH extended with node_modules/.bin, INIT_CWD, npm_lifecycle_event, npm_package_name, npm_package_version).

Inherits stdio from the parent so the user sees script output live. Returns Err on non-zero exit so install fails fast if a lifecycle script breaks, matching pnpm.