Replace Svelte example with runes (v5.0.0+) and rm deprecated onmousemove

[vincvdwal]

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[Fil]

Thanks! I think we also need to link to a different playground url.

(I pasted your changes and saved them to https://svelte.dev/playground/e65b5c87ae7e44239cef41ec3df28f52?version=5.2.7)

[vincvdwal]

Np! I was wondering, maybe it needs 2 versions, since v5.0.0 with runes is kind of new? I don't know if a lot of people still use Svelte v4.x.x or prior. But I was kind of struggling getting it working with the new runes, that's why I opened this PR. I also thought about removing the Typescript stuff since it's actually optional in Svelte

[Fil]

We don't want to make this documentation about svelte versions. Being up-to-date is good if you're starting a new project. The typescript stuff is not overwhelming, and can be helpful, so I think we can keep it.