MOSCOW — A Moscow court on Saturday rejected Russian opposition leader Alexei Navalny’s appeal against his prison sentence, even as the country faced a top European rights court’s order to free the Kremlin’s most prominent foe. Speaking before the verdict, Navalny urged Russians to stand up to the Kremlin in a fiery speech mixing references to the Bible and “Harry Potter.” A lower court sentenced Navalny earlier this month to two years and eight months in prison for violating terms of his probation while recuperating in Germany from a nerve agent poisoning that he blames on the Kremlin.