A bet builder combines multiple selections from the same match into one bet (e.g. Match Winner + Over 2.5 Goals for the same fixture).
Results use the same layout as /insights: a list of fixtures, where each fixture contains a bet_builders[] array.
Results only ever include active, non-suspended bet builders — there's no way to include suspended or expired ones yet (a dedicated /bet-builders/archive endpoint, mirroring /insights/archive, is planned). Pagination is not implemented yet — a fixed internal result limit is applied for now.