chore: upgraded start-basic to Tailwind CSS 4

[58bits]

We've just started testing Tanstack Start and began with the start-basic example. The first thing we did was upgrade to Tailwind CSS 4 - which is in this commit and PR. Probably just a drop in the bucket but hope this helps. Feel free to ignore if you have other plans.

[schiller-manuel]

this needs to be applied here i guess

#4606

[58bits]

I've tested this - npm install and npm dev and it all seems to be working fine. I thought this one might be worth updating as it's one of the first examples that's mentioned on the getting started pages. Would be happy to take a look at the others if that would help.

[KernelCode]

i think we need to update the docs ..

[birkskyum]

All examples / e2e have been updated to tailwind 4