chakra-core/ChakraCore ? reverse-engineered prompt

Build me a JavaScript engine library that I can embed in a C or C compatible app, with a simple C API and a lightweight command line host so I can run small scripts and print output to the terminal.

I want it to work on Windows, macOS, and Linux, and I want the project to be easy to build from source with the usual tools on each platform. Please make sure the engine can be compiled cleanly and that there are basic tests or sample usage so I can tell it is working. If anything in the current setup needs to be looked up in the latest docs online, do that too.

Keep it focused on the engine itself, not browser features or Node.js features. I mainly want a solid JavaScript runtime I can embed in another app and a straightforward way to build and run it locally.