On Saturday morning, as hundreds of far-right activists and lawmakers from across Europe gathered outside a conference center in the central Portuguese town of Figueira da Foz, a group of half a dozen men dressed in identical uniforms of khaki chinos, dark blue shirts, and sunglasses marched into the parking lot.On the lapels of their jackets, some wore the red and blue circular emblem of Patriot Front, the US white-supremacist group formed in the wake of the 2017 Unite the Right rally in Charlottesville, Virginia, and known for marching in large numbers while wearing masks and targeting left-wing events. When...