A 28-year-old man is brought to the trauma bay after a stab wound to the left 5th intercostal space at the midaxillary line. He is alert, BP 118/76 mmHg, HR 102/min, RR 22/min, and SpO₂ 94% on room air. Breath sounds are absent on the left side. Percussion is hyperresonant over the left hemithorax. Trachea is midline. Jugular venous pressure is normal. Chest X-ray shows a collapsed left lung with air in the pleural space but no mediastinal shift. What is the most appropriate next step?