fix(examples): fix codesandbox build

[saitonakamura]

Hey, @CodyJasonBennett , I saw that you've brought back path resolve in examples/vite.config.ts. I removed it on purpose so the codesandbox CI would work (it used to, but now it doesn't, not sure why). My idea is that examples are supposed to be run from the root with yarn dev, not from examples folder, and I highlighted it in https://github.com/pmndrs/react-xr/blob/master/CONTRIBUTING.md#run-locally for the newcomers. I apologize for not being clear enough in my PRs.

So, like, root vite.config will be responsible for local runs and examples/vite.config will be for codesandbox CI.

Example of codesandbox not working may be found in this PR, for instance
#294
https://codesandbox.io/p/sandbox/examples-j88rj5

[codesandbox-ci]

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Latest deployment of this branch, based on commit c52cb97:

Sandbox	Source
examples	Configuration

[saitonakamura]

Hey @CodyJasonBennett , are you ok with this ^ ?