A 35-year-old man is brought to the emergency department 30 minutes after a stab wound to the right lower abdomen (below the arcuate line, lateral to the rectus sheath). He is haemodynamically stable (BP 132/80 mmHg, HR 88/min). Abdominal examination shows a single stab wound with minimal bleeding, soft abdomen, no peritoneal signs, and normal bowel sounds. What is the most appropriate next step in management?