A 52-year-old woman from Chennai with a 2-month history of progressive cough, hemoptysis, and constitutional symptoms presents to the chest clinic. Chest X-ray shows right upper lobe cavitary infiltrates. Sputum smear microscopy is negative for acid-fast bacilli on three separate occasions. Culture on Löwenstein-Jensen medium at 37°C shows growth of acid-fast bacilli after 3 weeks. The colonies are yellow when exposed to light but revert to buff color in the dark. Biochemical tests show niacin negativity and nitrate reduction positivity. What is the most likely organism?