A 2-year-old girl from Delhi presents with a 3-week history of irritability, poor feeding, and constipation. Her mother noticed a firm, non-tender mass in the left upper abdomen during bathing. On examination, blood pressure is 145/95 mmHg (elevated for age), and there is a fixed, hard mass palpable in the left flank. Serum creatinine is normal. Abdominal ultrasound reveals a 7 cm heterogeneous mass arising from the left adrenal gland with areas of calcification. 24-hour urine metanephrines are markedly elevated (8-fold normal). Which of the following is the most likely diagnosis?