A 16-year-old boy with no significant past medical history presents to the emergency department with acute-onset fever, dyspnea, and cough over the past 48 hours, rapidly progressing to respiratory failure requiring mechanical ventilation. His family reports he started smoking cigarettes for the first time about three weeks ago. Laboratory results are notable for the absence of peripheral eosinophilia, but bronchoalveolar lavage fluid shows 30% eosinophils. What is the most likely diagnosis?