Joint Optimization of Relevance and Engagement in Multi-Task Ranking for E-Commerce with Efficient LLM Supervision. - Luming Chen; Jiaqi Xi; Raghav Saboo; Kenny Chi; Martin Wang; Sudeep Das; Danny Nightingale; Aditya Dodda; Elyse Winer; Akshad Viswanathan (CoRR, 2026)