This is The Close-Up , where the biggest names in entertainment explain the story behind their latest personal style statement. For one heart-racing hour every Thursday, The Pitt viewers spent 15 weeks this spring seeing Supriya Ganesh as fan-favorite resident Dr. Samira Mohan in exactly one outfit: black, ER-proof scrubs and cushioned sneakers, with a stethoscope slung around her neck. Don't let the onscreen uniform fool you, though. In the 18 months since the Columbia University alum made the leap from MCAT tutoring to a recurring role on one of TV's most critically-acclaimed medical dramas, she’s proven her red carpet bona fides. "I love almost getting to play dress up and having fun with it," Ganesh tells Marie Claire .…