FaxCoreDev/FaxCore-eV6-API ? reverse-engineered prompt

Build me a clean sample project for the FaxCore eV6 REST API that makes it easy to try the main workflows without guessing.

I want simple examples for signing in with client credentials, listing messages and domains, sending a fax with an uploaded PDF, checking read and delete state, forwarding or delegating a message, updating a subject or tracking record, and a couple admin tasks like creating a domain and updating a user profile. Please include versions that work from the command line and from a small .NET console app, and if it helps, add a few JavaScript and curl examples too.

Make the setup easy to run with environment variables for the base URL, client ID, client secret, token, and upload file, and keep secrets out of the repo. Use the local OpenAPI file and current docs online if you need to. I’d like the samples to be organized in a way that a new person can follow, with clear names and a predictable structure.