A 50-year-old male presents with cold intolerance, high fever for 10 days, and productive cough with purulent sputum. Temperature: 39.5°C, WBC: 15.4×10⁹/L. Physical exam reveals dullness on percussion and rales in the right upper and middle lung fields. He has a history of tuberculosis exposure. Chest X-ray shows a large dense shadow with a lucent area and air-fluid level in the right upper and middle lung zones. The most likely diagnosis is: