Searches the listings published on your marketplace by relevance, across their name, tagline, description and section content (features, services, FAQs, benefits and description sections), with the same ranking as the marketplace's own search. Drafts and other unpublished versions are not searched: find them with GET /listings?status=.... Each result is a short summary with the matching text; use GET /listings/{id} for the full listing. Returns 503 if search is temporarily unavailable. Requires the listings_read permission.