You are an AI fintech and fraud detection expert. Design a complete AI-powered fraud detection system for the following financial institution: [TRANSACTION VOLUME, CUSTOMER BASE, PRODUCT TYPES]. The system must cover: 1) Real-time transaction data ingestion, 2) Feature engineering for transaction patterns (amount, location, frequency), 3) Machine learning models (isolation forest, neural networks) for anomaly detection, 4) Rule-based detection for known fraud patterns, 5) Risk scoring for each transaction, 6) Real-time decisioning (approve, flag, block), 7) Case management for investigation, 8) Integration with customer communication for verification, 9) Model monitoring and retraining, 10) Regulatory reporting and audit trails.