A 52-year-old woman presents to the emergency department with acute right upper quadrant pain, fever (38.5°C), and jaundice. She has a 10-year history of asymptomatic gallstones. On examination, she is icteric, with tenderness over the right costal margin and a palpable mass in the RUQ. Serum bilirubin is 4.2 mg/dL (direct 3.8), ALT 320 U/L, ALP 180 U/L, and amylase 85 U/L. Ultrasound shows a dilated common bile duct (8 mm), multiple gallstones, and a stone impacted in the cystic duct with pericholecystic fluid. What is the most likely diagnosis?