A 28-year-old man is brought to the emergency department following a high-speed motor vehicle collision. He was the driver and struck a tree head-on at 80 km/h. On arrival, his blood pressure is 95/62 mmHg, heart rate 118/min, respiratory rate 28/min, and GCS 15. Abdominal examination reveals a rigid, distended abdomen with severe tenderness in the epigastrium and left upper quadrant. There is bruising over the left flank. A focused assessment with sonography for trauma (FAST) shows free fluid in the peritoneal cavity. CT scan with IV contrast demonstrates a shattered spleen with active extravasation and a laceration of the pancreatic body with disruption of the main pancreatic duct. The patient remains haemodynamically unstable despite 2 units of packed red blood cells. What is the most appropriate next step in management?