PUBLISH_ARGS JSON fallback

Trap: JSON.parse(process.env.PUBLISH_ARGS || '') looks like a harmless missing-value default, but an unset variable becomes an unhandled SyntaxError before deliberate validation runs. Fix: use a valid JSON fallback such as '{}' in runnable Publish entry points, because JSON.parse() must receive JSON and subsequent required-field validation can emit the intended contextual error.