She liked to mimic her grandmother, so a week ago, Nyiah Courtney got her hair braided. “We twins now,” the smiling 6-year-old told Andrea Courtney. It was one of the last times the two talked. Nyiah was fatally shot Friday night while walking to her nearby home with her mother, father and older sister in the Congress Heights neighborhood of Southeast Washington. Police said the shots came from a gray, four-door sedan passing the commercial corner of Martin Luther King Jr. and Malcolm X avenues, striking Nyiah, her mother and four others, among the latest victims in a city struggling...