It’s official: Zohran Mamdani has been elected mayor of New York City, raising the flag of the far left over Gotham. And if you believe the hype or the fears of his critics, then the 34-year-old Ugandan-born Muslim democratic socialist is poised to remake the Democratic Party, thrilling young voters, mainstreaming socialism and anti-Zionism, and offering himself as the starkest possible contrast to that other New Yorker in the White House.