The title of playwright Jonathan Spector’s Broadway debut, “Eureka Day,” refers to a private elementary school nestled in the hills of Berkeley. It’s the kind of place in which the library, where the play is set, categorizes books as “fiction,” “non-fiction,” or “social justice.” One poster decorating the walls declares, “We Are the Resistance;” another acknowledges that the school “is located on the unceded territory of the Chochenyo-Speaking Lisjan Ohlone People.”