A powerful, slow-moving nor’easter continued to batter the Northeast on Sunday, leaving more than 100,000 customers without power and threatening coastal communities with another round of flooding at high tide. The storm remained just south of Long Island and east of northern New Jersey and was expected to linger in the region for about another day. Forecasters said the worst remaining rainfall would stretch from northern New Jersey through New York City and Long Island into southern New England. The storm killed a New York City housing authority worker Saturday and has flooded roads, disrupted air travel and cut off highway access to Hatteras Island.