Enable support for replicas to improve high availability

[sig5]

Add support for enabling replicas in the database engine to increase data redundancy and improve high-availability. This feature should:

• Allow users to configure one or more replicas for data synchronization
• Ensure replicas receive all committed changes from the primary node
• Provide options to monitor replica status and health
• Document best practices for deploying and managing replicas

Implementing replicas will help scale read operations and provide fault tolerance.