Guardian angels are scattered throughout the office of Connie Stephens, who for 27 years has worked to guard the safety of local children. The design motif carries through other offices inside the Court-Appointed Special Advocates space on Washington Street, where staff work within earshot of shaking baby rattles and a clanging toy glockenspiel in a room where children visit with family members. Stephens, the agency’s executive director, is stepping down next month, said the angel statuettes are “symbolic of the kind of work we do.”