fix: allow {@html await ...} and async snippets on the server

[Ocean-OS]

Fixes #16816
Fixes #16811

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[changeset-bot]

🦋 Changeset detected

Latest commit: 4bd8d83

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

This PR includes changesets to release 1 package

Name	Type
svelte	Patch

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[github-actions]

Playground

pnpm add https://pkg.pr.new/svelte@16817

[dummdidumm]

👍 (sneaked in a similar fix for snippets)