Convert Desktop C# App to API

I have an existing C# desktop application that handles batch-oriented data processing. I now need the same logic exposed as a RESTful API that can run as a service on our Windows Server.

You will take the current codebase, separate the processing engine from the UI, wrap the engine in modern Web API endpoints, and deploy the finished service on the server. Configuration files, logging, and basic authentication should remain just as straightforward as they are now on the desktop version.

Deliverables:
• Refactored C# source with REST endpoints
• IIS or Windows Service setup scripts and instructions
• Post-deployment test proving the batch processor runs through the API call successfully
• Brief README covering build, configuration, and usage

The desktop app is already clean and well-documented; I will provide the full solution and a sample data set for local testing. Once the API is live on the server and passes the same batch tests we use today, the project will be considered complete.