chore: update UnoCSS

[ackzell]

I want to use UnoCSS on a project I am building, but I noticed that tk is using an older version. So bumped into compatibility issues and I decided to upgrade it in a local fork. This has worked for me so far, thus creating a draft PR.

If you find it useful you can take the changes. I will probably be updating other places where in order for the theme vars to be picked up (bg- and text- classes I noticed so far) the syntax is slightly different. You can see an example in the callouts.ts component.

Also, the e2e stopped working for me, so I used some ai help to modify the test and make it pass again (it was receiving an oklch value when expecting an rgb if I recall correctly)

(Perhaps I overcomplicated myself and didn't need all of this, but I just couldn't make some things work for me the way I wanted them to. So here I am)