A 38-year-old woman from rural Maharashtra presents to the emergency department with severe metabolic acidosis (pH 7.18, HCO₃⁻ 12 mEq/L), tachycardia (HR 118/min), tachypnea (RR 28/min), and profuse diaphoresis. She reports accidental ingestion of a pesticide 4 hours ago while working in her field. Her core body temperature is 39.2°C despite ambient temperature of 28°C. Serum salicylate level is 68 mg/dL (toxic range >60 mg/dL). Arterial blood gas shows respiratory alkalosis superimposed on metabolic acidosis. Which of the following best explains the thermogenic mechanism underlying her hyperthermia?