Photo: Caean Couto/Getty Images As he clears the 100-day mark of his unprecedented mayoralty, just how popular is Zohran Mamdani ? New polls from Marist College and Emerson College offer a window into the support the 34-year-old socialist enjoys as well as enough fodder for his detractors. Marist found that 48 percent of New Yorkers approved of Mamdani’s job performance, while 30 percent disapproved. (Twenty-three percent were unsure.) Fifty-six percent of New Yorkers said things were moving in