Event Sourcing over CRUD for Financial Transaction Audit Trails

Decision: Replace standard CRUD in PostgreSQL with Event Sourcing for financial transaction audit trails. Context: Compliance required history of transaction #8821. Standard CRUD overwrites previous states. Triggers rejected for lacking business context. Solution: Kafka for immutable domain events + Postgres materialized views. Reference: Martin Fowlers Event Sourcing Pattern. Files: src/services/transactionService.ts, src/events/eventStore.ts.