Get Zaxby's national reference menu

Returns Zaxby's full national reference menu: every category and product, with description, calories, image, and a full recursive customization tree (size/protein/sauce choices, each with its own real price delta). This is national reference data, not store-priced -- most items list cost 0 because real pricing is store-specific and requires a signed-in ordering session this endpoint does not have. Many items price entirely through a required customization selection rather than a base cost, so cost 0 on an item is expected, not a bug.