carbon-language/carbon-lang ? reverse-engineered prompt

Build me a working version of Carbon Language from this repo so I can clone it, follow the docs, and actually build the toolchain locally.

I want the project to feel polished for someone trying out an experimental successor to C++. Make sure the compiler, tests, examples, and supporting tools all build cleanly, and that the main docs explain how to get started without a lot of guesswork. If there are missing or broken pieces in the current setup, fix them so the repo has a smooth first run experience.

Also make the website and README feel consistent with the current state of the project, since this is meant to be an experimental language and not a finished product yet. If you need to look up current docs or best practices online, go ahead and do that.