Get one Shake Shack location's full menu

Returns one Shake Shack location's full menu as a category tree: every category and its products, with name, description, base calories, allergens, a promotional/dietary badge when published (e.g. "LIMITED TIME ONLY", "VEGETARIAN"), image, and a full customization tree (size, additions, removals, allergen flags), each choice carrying its own price and calorie delta. location_id comes from GET /shakeshack/nearby. Many items, most notably burgers, price entirely through a required size selection rather than a base price, so price is commonly 0 for those items -- the real price lives on the size modifier's own choices.