formkit/auto-animate ? reverse-engineered prompt

Build me a small JavaScript library that makes UI changes animate smoothly with almost no setup.

I want it to work in plain web apps, and also with React and Vue, so a developer can just drop it onto a parent element and have things like items being added, removed, reordered, or resized transition naturally instead of jumping around. It should feel simple and lightweight, with a nice default experience and clear docs on how to use it in a few common setups.

Also include a few examples I can run locally, plus a way to extend it with plugins if that fits the design. If anything is unclear, look up the current docs online and match the existing behavior as closely as possible.