Act as a Solutions Architect. We have a massive, monolithic Java application handling user management, payment processing, and inventory in a single codebase. This is causing slow deployment cycles and 'stepping on toes' between teams. Design a high-level migration blueprint to transition this to a microservices architecture using the Strangler Fig pattern. Your plan must address: 1) Database decomposition strategies (shared database vs. database per service), 2) Inter-service communication (synchronous REST vs. asynchronous event-driven messaging using Kafka/RabbitMQ), 3) Handling distributed transactions and eventual consistency, and 4) Authentication and security across service boundaries. Provide a step-by-step phased approach prioritizing the extraction of the 'low-hanging fruit' services first.