Full-text faceted search

This is the main marketplace search endpoint.

Use it for:

• global search bars
• category and filter pages
• any browse/results screen where users need discoverability

Behavior:

• Accepts free-text query, facet filters, sorting, and paging input.
• Returns matching items plus facet aggregations so the UI can render filter chips and counts.

Good to know:

• Results are cached briefly (~30s) for identical request bodies.
• Different JSON bodies generate different cache keys.