v3 SvelteKit Onboarding - pin the sv CLI version to avoid Tailwind v4 for now

[endigo9740]

Link to the Page

https://next.skeleton.dev/docs/get-started/installation/sveltekit

Describe the Issue (screenshots encouraged!)

Currently the v3 SvelteKit onboarding documentation uses the sv to scaffold a new project using this command:

npx sv create --template minimal --types ts my-skeleton-app

This should be pinned to the last version prior to the the Tailwind add-on rolling over to v4.

Note that this change hasn't been merged at the time of writing this message, but we need to do this asap to avoid a gap where folks can unintentionally install Tailwind v4 by mistake. Which would leave folks in a state where Skeleton is not functional.