A 68-year-old woman with hypertension and osteoarthritis presents with rising creatinine and edema after starting high-dose ibuprofen. Labs show BUN 42 mg/dL, creatinine 2.1 mg/dL (baseline 1.0), urine sodium 10 mEq/L, FeNa 0.5%, and bland urinary sediment. What is the most likely diagnosis?