feat: add rounded corners

[marriaga158]

Added corner radius as a setting as well as default rounding for Windows 11 and MacOS

I only have a Windows 10 machine available to me for development, so testing on those OSes should be done to confirm default rounding is functioning as intended

Implements planned feature https://github.com/dvx/lofi/projects/5#card-90705511

[stamoun]

Thanks a lot for taking the time to do this!

I should be able to have a look at your PR this week.

[stamoun]

I noticed another issue (other than the bars and menu buttons disappearing).
When I switched to one of my other monitors on my Mac, the transparent background was white as follows:

Not sure if it's a Mac only issue (haven't tested on windows).
I don't think it's a showstopper for this feature though. I'd create a new issue for that.

[stamoun]

Good stuff though, I like the rounded corners! 🤗

[marriaga158]

Updated with the suggested changes, there's still a lingering issue where on larger sizes the corner radius can clip the menu buttons. Going to investigate if there's a way to automatically move them inwards as a solution