It was minus-61 degrees Fahrenheit in Yakutsk, about 300 miles south of the Arctic Circle, on Saturday, but the people still came. The scene was like something out of a post-apocalyptic movie: a queue of dimly visible figures against the whited-out backdrop of a snow squall. They had come to show solidarity with Alexey Navalny, the imprisoned leader of the Russian opposition, who had been arrested upon his return from Germany where he was recovering from an attempt on his life.