Get the best listings for a collection sorted by price ascending. Optionally filter by item traits using the 'traits' query parameter with a JSON array of trait filters. Multiple traits are AND-combined (items must match all). Note: results are not deduplicated by token ID — if a token has multiple listings, each listing is returned individually. Filter client-side if you need unique tokens. Example: ?traits=[{"traitType":"Background","value":"Red"}]