Anthropic Batch API for Asynchronous Multi-Tenant AI Processing: Cutting Claude Costs by 50% Without Sacrificing Feature Responsiveness

Implement FastAPI endpoints that queue AI feature requests (document summarization, bulk classification) into Anthropic's Batch API for 50% cost reduction, then use PostgreSQL LISTEN/NOTIFY to push results back to React 19 dashboards in real-time when batch jobs complete—ideal for CitizenApp's heavy users.