Analyze the following user story and extract structured requirements.
User Story: {user_story}

Return a JSON object with exactly these fields:
- modules: list of feature modules (e.g. ["Login", "Cart", "Checkout"])
- risk_areas: list of high-risk areas (e.g. ["Authentication", "Payment Flow"])
- priority: overall priority, one of: Low, Medium, High, Critical
- confidence_score: your confidence in this analysis (0.0 to 1.0)

Return ONLY valid JSON, no markdown, no explanation.
