Remove fade value and use animation for checkbox

[ylvaselling]

Switches the fading checkbox from this:

2026-03-30.11-07-52.mp4

To this:

2026-03-30.11-07-34.mp4

This has the benefit of:

• Feels more responsive
• More performant as it doesn't need the fade value

[WeirdRubberDuck]

Nice! The animation shows an ugly "jack" when the icon size is increased, however. It would be great if we could fix this now rather than later, to make the component more usable.

It might be solvable by just increasing the background size to make sure the edge is never visible

Here's how it looks for an md sized icon:

incon.mp4

Otherwise, it looks great