MOSCOW — A Russian judge on Monday ordered opposition leader Alexei Navalny jailed for 30 days, after the leading Kremlin critic returned to Russia from Germany where he was recovering from nerve agent poisoning that he blames on President Vladimir Putin’s government. The ruling followed a hastily set up court hearing at a police precinct where Navalny was being held since his arrest at a Moscow airport on Sunday evening, which sparked sharp reactions both at home and around the world. A crowd of Navalny supporters outside the precinct shouted “Shame!” as the judge announced the ruling and Navalny’s allies immediately called for protests.