Stephen R. Laverty, the embattled chief executive of Beverly (MA) Hospital, could resign as soon as today, according to physicians and healthcare executives with ties to Northeast Health System Inc., the hospital's parent organization. Laverty came to Beverly in 2000 and in April, the hospital's doctors took a vote of no confidence in him. Nurses took a similar vote last month. Laverty is known for his combative management style at Beverly and other hospitals where he worked, and has disparaged some doctors, according to physicians at the hospital.