umijs/qiankun ? reverse-engineered prompt

Build me a simple micro frontend demo app using qiankun.

I want one main app that can load a couple of smaller apps into the same page, with a clean switch between them and the ability to unmount them when I leave that part of the app. Please make it show basic isolation so one micro app does not mess with another, and add a small example of styles and shared data passing between the host and child apps.

If it helps, look up the current docs online and follow the recommended setup for qiankun 3 so the example actually works. I’d like it to be easy to run locally, with clear starter code for both the host and the micro apps, plus a simple README that explains how to start everything and what each app is doing.