fix: update to @vitejs/plugin-react v6 remove babel and add memoization

[joshdonnell]

With @vitejs/plugin-react v6, Babel support is dropped, meaning the auto memoization we get from the Babel compiler is no longer included.

This PR:

• updates @vitejs/plugin-react to v6
• Removes the babel-plugin-react-compiler from vite
• Updates memoization where required to prevent re-renders

[rdgout]

@joshdonnell I am wondering why you choose to remove the react compiler instead of using the new way to include the react compiler. Removing automatic memoization will make this start kit worse in every way possible.

The release notes clearly state how to keep the react compiler by using the rolldown plugin.