Function handle_package_command 

pub fn handle_package_command(
    args: &[String],
    handler: &dyn PackageHandler,
    out: &dyn PackageOutput,
    platform: DispatchPlatform,
) -> Option<PackageOutcome>

Mirrors the verbatim status/error strings and exit-code mapping of handlePackageCommand (package-manager-cli.ts:676-887).