Integrate Darts for Time-Series Anomaly Detection

Enhance your `TransactionMonitor` agent by integrating Darts. Create a new tool, `analyze_transaction_patterns`, that takes transaction data from `fetch_transactions` and uses Darts to identify statistically significant anomalies (e.g., sudden spikes, unusual frequencies). The agent should then interpret these anomalies to determine potential suspicious activity. Consider how to pass the time-series data to the Darts tool effectively.