A 58-year-old woman with CKD stage 3b (eGFR 35 mL/min/1.73m²) secondary to hypertension is found on routine screening to have serum calcium 7.2 mg/dL (corrected), phosphate 4.8 mg/dL, and iPTH 180 pg/mL. She is asymptomatic. Alkaline phosphatase is 92 U/L (normal 30–120). A bone biopsy shows low bone turnover with minimal osteoid. Which of the following is the most likely diagnosis and the primary mechanism driving this bone pathology?