Create a contract library for functional call handling

[this-Aditya]

Currently, inter-microservice calls and related interfaces are scattered across the codebase, and delegate-service handles these calls without verifying the structure or response. To improve this, we should create a dedicated contract library.
This library will collect all service contracts and related types in one place, making it easier to manage, update, and share them between services. By centralizing these definitions, we can reduce duplication and ensure consistency in how service calls are handled.