PERTH AMBOY, N. J.—On a visit to a sprawling warehouse in northeast New Jersey, employees of luxury resale platform The RealReal buzzed around with racks of clothing and accessories like they have for years, getting sellers’ submissions ready to list. But lately they have been accompanied by an AI-infused program that executives hope will speed up the time to sell items and reduce their need to add as many workers over time. Called Athena, the technology proposes item descriptions, suggests pricing and, crucially for a company that receives millions of goods a year to sell on consignment, helps discern authentic…