Add support for p3 colorspace

[Why-Not-Us]

According to the README.md:

"Some limitations might instead regard the platform the website is running on. One of the examples is color-fidelty.
Apple Wallet uses a color scheme called Display-P3, which is widely available in native applications, but not yet available in browsers.
For this reason, some colors might result less brighter or just different.

At the time of writing, only Safari supports this color scheme and, for this reason, it makes no sense to work with it.

It is also known that, currently, Apple Wallet applies a really small gradient on the background color, which changes color perception and which seems to be different from color to color. I've been able to find no details on how this gradient is composed."

I noticed that webkit added increased support for P3 to its colorpicker in ios 18.4 and it looks like this is now supported across browsers, so creating this to track implementing it (I'm toying with a similar app and will try to contribute back my findings):

https://webkit.org/blog/16574/webkit-features-in-safari-18-4/
https://caniuse.com/?search=Display-P3

[alexandercerutti]

Hello @Why-Not-Us, thanks for using pkvd!

I'm well aware about the wide support to Display P3 in browsers. Indeed, it is my intention to add it.

However, this project hasn't been touched for years now and I'm re-designing it from scratch in order to support a lot of features more, like the new designs for passes, NFC and many many things more.

Sadly, I don't have a estimated time of shipping, since we are still working on the design details, and I'm pretty busy.

Nonetheless, I really appreciate your interest in this project. If you are willing to work on it for the current version and open a pull request, I'll be pretty happy to review it and talk about it.