A 28-year-old woman presents with right lower quadrant pain for 48 hours, fever (38.8°C), and vomiting. On examination, she has severe tenderness in the RLQ with guarding and rigidity. WBC is 16,200/μL. Ultrasound shows an appendix measuring 10 mm with a hyperechoic focus suggesting perforation, and a loculated fluid collection (4 × 3 cm) adjacent to the appendix. What is the most appropriate management strategy?