The Senate cleared a decades-long partisan impasse over how to address gun violence on Thursday night, passing a modest set of gun safety measures that would enhance background checks for younger buyers and fund new mental health programs. The bill passed by a vote of 65 to 33, garnering support from the entire Democratic caucus and 15 Republicans, on the same day the Supreme Court expanded the scope of gun rights in a landmark ruling. “This is the sweet spot … making America safer, especially for kids in school, without making our country one bit less free,” Senator Mitch McConnell, Republican of Kentucky and the minority leader, said Thursday.