All the code has been move to the twitter-threading repository.
This is a simple UI written in HTML and JavaScript for the twitter-threading tool by @svpino.
You can enter your Twitter thread and download it as a yaml file in the format supported by twitter-threading.
The page is static so you can just clone the repository and open index.html in your browser.
Alternatively, the page is also deployed on Netlify: https://twitter-threading-editor.netlify.app/.