Optional per-category sub-ratings submitted together with the host review. Only effective for channels that support category ratings (currently Airbnb and Zhenguo). When provided without host_review_score, the overall_rating value is used as the review score. Supported keys: overall_rating, cleanliness, communication, respect_of_house_rules, recommend. Each rating value is between 0 and 5 (recommend is a boolean 0/1).