[Feature]: png embedded tldr
### What's the feature?

The idea comes from draw.io and would be good to adopt for “tldr”:
PNG images can contain data that is not displayed. This data could be used to embed the “tldr” source of the generated image.
Then, for example, myShape.tldr.png can be displayed by common image viewing programs, but “tldr” can process it directly as a “tldr” graphic.

By the way: “tldr” is a great and very useful tool!

### Where would you like this feature?

The developer package

### Contact Details

_No response_

### Code of Conduct

- [x] I agree to follow this project's Code of Conduct