Screen a registered ad creative by ad_id (v1.1)
POST/api/v1.1/ad-blocking
Screen an already-registered ad creative — identified by ad_id (must be status='ready') — for GARM brand-safety + policy violations. JSON body, no file upload. The v1 POST /ad-blocking multipart-upload route is unchanged; this v1.1 route reuses a creative already in the Ad library.