rahulmalhotra/HTTPCalloutFramework ? reverse-engineered prompt

Build me a lightweight Apex framework for Salesforce HTTP callouts that makes it easy to manage API requests from custom metadata instead of hardcoding everything in code.

I want one simple service for normal synchronous callouts, plus support for asynchronous callouts using continuation so it can work from both Visualforce and Lightning. It should let me define things like endpoint, request method, headers, body, and timeout in a custom metadata record, then create the request and send it from that stored config.

Please also add mock classes so I can test one callout or multiple callouts in a single transaction, and include proper test coverage so it deploys cleanly. Make it feel ready to install into a Salesforce org, with the custom metadata type, a sample record for demo use, and a clear example of how to call it from Apex. If you need to check current Salesforce docs for continuation syntax or test patterns, go ahead and look them up.