[docs] Add and revise Base UI + Create React App examples

[mapache-salvaje]

Part of #36193

• add Base UI + Create React App (JavaScript) example
• clean up Base + CRA TypeScript example
• add more details to READMEs
• improve startup pages

Startup page before:

After:

[mui-bot]

Netlify deploy preview

https://deploy-preview-36825--material-ui.netlify.app/

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Generated by 🚫 dangerJS against 2da036e

[mapache-salvaje]

I know my startup page isn't the most beautiful thing in the world, but I think it's an improvement nonetheless! 😅 I wanted it to be helpful but didn't want to invest too much time into making it pretty.

[michaldudak]

I wonder if we should invest in CRA examples as it's no longer a recommended way of starting a React project (reactjs/react.dev#5487 (comment), https://react.dev/learn/start-a-new-react-project)
Having Vite as a SPA example seems to be more future-proof

[mapache-salvaje]

I wonder if we should invest in CRA examples as it's no longer a recommended way of starting a React project (reactjs/react.dev#5487 (comment), https://react.dev/learn/start-a-new-react-project) Having Vite as a SPA example seems to be more future-proof

@michaldudak my goal in #36193 is to reach parity with Material UI for Base and Joy examples. I think CRA is still relevant and worth keeping around, even if it is falling out of fashion.

I'll move on to Vite examples from here so we'll have those ready before the stable release. After that I think Next.js and Tailwind CSS will be the highest priorities.

[mapache-salvaje]

I know CRA isn't a big priority but we might as well merge this since it's here. 😅 Can I get a final review?

[mapache-salvaje]

...Or maybe we don't want any CRA examples anymore? See: #37367

[michaldudak]

Let's go ahead and add these since you've already spent some time on them. I wouldn't create any new ones after that, though.