contrastio/recorder ? reverse-engineered prompt

Build me a simple browser app that lets people record their screen and webcam without installing anything.

It should open in Chrome, let the user choose screen only, camera only, or both together, then show a live preview before recording. When both are on, the camera should appear in a picture in picture style overlay while the screen is being captured. Add clear Start Recording and Stop Recording controls, and when the recording is done, let the user save the video file locally.

Please keep it private and local, with no tracking or uploading. Make the interface clean and easy to understand, since I want this to feel like a quick tool anyone can use right away. If you need to check the current browser APIs or docs, go ahead and look them up online.