MADISON, Wis. — Republicans pushed today for Wisconsin to become the first state in the nation to prohibit transgender public school students from using a bathroom or locker room assigned to the gender with which they identify.Opponents, including students who stood and sat on the floor in a packed hearing room, argued the proposal is a violation of federal civil rights law. The soonest that the state’s GOP-controlled legislature could act on the bill is January, and it’s unclear whether the measure has …