Vendors shared/playground-design-system/ into a plugin's
playground/vendor/playground-design-system/ tree so each plugin stays
standalone (no marketplace-rot dependency at runtime).
Features:
- Generates MANIFEST.json with SHA-256 per file, source commit hash, sync date
- Drift detection: refuses overwrite if vendored file changed since last sync
- --force flag to override drift
- Injects "DO NOT EDIT" header into copied CSS files
- Pure Node.js, zero npm deps (uses fs.cp from Node 16.7+)
Usage: node scripts/sync-design-system.mjs <plugin-name> [--force]
