Ashish-Bansal/audio-only-youtube ? reverse-engineered prompt

Build me a Chrome extension that makes YouTube play audio only so I can listen to songs and videos without loading the full video. It should automatically switch on when I open a regular YouTube video, save bandwidth, and let me toggle it off and on from the extension icon in the toolbar. When audio only mode is off, the page should refresh back to normal video playback. When it is on, the icon should look different so it’s easy to tell, maybe grayscale versus normal color.

Please make it work for standard YouTube videos, but it does not need to support live streams. I’d like it to be a proper extension I can load unpacked in Chrome and test locally. If you need current docs or examples for anything, look them up online first.