vuejs/core ? reverse-engineered prompt

I want to create my own progressive JavaScript framework for building web UIs, something similar in spirit to Vue.js. It should be easy for someone to adopt incrementally, meaning they could just drop a script tag onto an existing page to add some reactivity, or they could use it to build a complex single-page application from scratch.

The core feature should be a modern reactivity system. When a developer changes a JavaScript variable, the corresponding parts of the UI on the web page should update automatically without any manual DOM manipulation. The whole thing should be built around a component-based architecture, allowing users to create reusable, self-contained chunks of UI with their own logic and display. Let's build the entire framework using TypeScript to keep it type-safe and maintainable.