A 28-year-old woman from Delhi presents with a 3-year history of irregular menstrual cycles (amenorrhea for 2–3 months alternating with heavy bleeding). She reports progressive weight gain (8 kg over 2 years despite diet control), hirsutism on face and abdomen, and acne. On examination: BMI 29 kg/m², blood pressure 128/82 mmHg, Ferriman–Gallwey score 12. Pelvic ultrasound shows bilateral ovarian cysts (8–10 mm) with increased stroma. Fasting blood glucose 102 mg/dL, fasting insulin 18 mIU/L (normal <12). LH:FSH ratio 3.2:1. What is the most likely diagnosis and the primary pathophysiologic defect?