Beto O’Rourke barnstormed through northern Virginia yesterday in a minivan, making several stops to address enthusiastic crowds. Our correspondent caught up with him in the backyard of Fairfax County School Board Member Tammy Kaufax (Lee District), where he presented his presidential vision to about 100 supporters. O’Rourke, a former congressperson from El Paso, Tx., highlighted inequities to minorities under the…