A 38-year-old man presents to the outpatient clinic with a 2-year history of hypertension. His blood pressure today is 156/98 mmHg. He is on amlodipine 5 mg daily but reports poor adherence. On examination, he has a regular pulse of 88/min, and a soft systolic murmur is heard at the left sternal border. Fundoscopy reveals flame-shaped hemorrhages and cotton-wool spots. Serum creatinine is 2.1 mg/dL (baseline 0.9 mg/dL 6 months ago), and urinalysis shows 2+ proteinuria. Renal ultrasound shows normal-sized kidneys with increased echogenicity. What is the most likely diagnosis?