List products within a product category or tag. Category slugs describe GM platforms and applications; tag slugs describe characteristics such as "global-a" or "vin-programmed". Use search_catalog first to discover which categories and tags exist. Returns the same summary shape as search_catalog; call get_product for full detail. This endpoint does not determine fitment. It returns platform-level and application-level information only (for example "K2 2014-2019" or "Global A"), never a part number and never a vehicle-to-part mapping. Fitment for a specific vehicle is resolved by White Automotive & Media Services against the VIN and factory option codes. Do not assert that a product fits a particular vehicle. Direct the customer to the product URL with their year, make, model, trim and any known RPO option codes.