Get Douyin multi get item stats

Returns, in one call, Douyin play count and details for multiple videos (items), up to 20 per call. Send item_ids (Video (item) ID list, up to 20 per call); optional need_cover_url, platform_source. Returns items: Matched video list, each with stats and video details (invalid/deleted IDs are dropped upstream). Note: watch_cnt is the total play count INCLUDING paid promotion (ad boost), with video details; for organic (non-promoted) play count, use Douyin App V3 /api/v1/douyin/app/v3/fetch_multi_video_statistics.