lnsflive/eco-core ? reverse-engineered prompt

Build me the public eco core project so people can scaffold a new app with npx create-eco and then use the @eco-dev/* packages to add on from there.

I want this repo to be a self contained TypeScript monorepo that installs, builds, and tests cleanly on its own, with the scaffold working out of the box and the shared packages ready for other projects to consume. Make sure the public pieces are polished, the setup feels easy to use, and the docs explain how to get started without any confusion.

If anything needs checking against current package docs or best practices, look it up online and keep the result simple and practical.