salesforce/lwc ? reverse-engineered prompt

Build me a Lightning Web Components project that gives me the core engine and compiler, plus a simple playground where I can create a few web components and see them render in the browser.

I want it to feel like a real framework repo, not just a demo, so set it up with a clean developer experience, basic tests, and a simple way to run it locally. Include a few example components that show common things like passing data, reacting to clicks, and rendering lists. Also add enough docs so someone new can understand how to start using it and how to contribute.

Keep the code organized and modern, and make sure it matches the idea of an enterprise grade web components foundation. If you need to check the latest LWC guidance or behavior, look up the current docs online and follow that.