feat: precompress prerendered .md and .mdx files

[sirkostya009]

closes #15891

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🦋 Changeset detected

Latest commit: 030ad15

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@sveltejs/adapter-node	Minor
@sveltejs/adapter-static	Minor
@sveltejs/kit	Minor

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