Charting suggestion: Copy as image

[arendjr]

@mies suggested to add a feature to the charting library for allowing "copy image to clipboard". I think it's a useful feature, though it may not be the most trivial with our current SVG-based approach.

I still think it makes sense to migrate the charting library to a canvas-based approach (powered by WebGL/WebGPU), which actually would make this rather trivial to implement, so my suggestion would be to wait for that first.