YORBA LINDA, Calif.—The mother of a Southern California boy killed in a road rage shooting remembered him Saturday as a six-year-old with a vocabulary beyond his years who exuded warmth and tenderness. “He gave us such joy, giving us purpose to our life. I felt so honored to be Aiden’s mommy,” Joanna Cloonan said at an open-casket memorial service for Aiden Leos. The boy was fatally shot in the abdomen on May 21 while seated in the back seat of a car driven by Cloonan, on State Route 55 in the city of Orange. According to accounts from the mother and witnesses who stopped to help her, another car cut her off, she responded with a hand gesture, the car slipped in behind her, and someone inside fired a shot through the rear of her car. A reward for information leading to the arrest of a suspect has grown to …