A 42-year-old woman presents to the emergency department with sudden onset right upper quadrant pain radiating to the right shoulder, associated with nausea and vomiting for the past 6 hours. She is overweight (BMI 32 kg/m²) and has a history of multiple pregnancies. On examination, she is afebrile (37.2°C), heart rate 98/min, blood pressure 128/82 mmHg. Right upper quadrant tenderness is elicited, and Murphy's sign is positive. Ultrasound abdomen shows a 1.8 cm stone in the gallbladder fundus with a thickened gallbladder wall (5 mm) and pericholecystic fluid. What is the most likely diagnosis?