You are a Solutions Architect. A large financial institution runs a legacy monolithic core banking system written in Java 8. Design a high-level migration strategy to transition this system to an event-driven microservices architecture on Kubernetes. Address the following points in your plan: 1) Database decomposition patterns (per service vs. shared database), 2) Transaction management and data consistency (SAGA pattern implementation), 3) Handling regulatory compliance and audit trails during the transition, and 4) Strangler Fig pattern application for zero-downtime deployment.