A 42-year-old Indian woman presents with a 2-month history of progressive dyspnea, hemoptysis, and constitutional symptoms. Chest X-ray shows bilateral pulmonary infiltrates with cavitation. ANCA serology is positive for c-ANCA (cytoplasmic anti-neutrophil cytoplasmic antibodies) with anti-PR3 specificity. Serum creatinine is 3.2 mg/dL, and urinalysis shows dysmorphic RBCs with RBC casts. What is the most likely diagnosis?