fix: run deferred effects in async components

[Ocean-OS]

Closes #16691

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[changeset-bot]

🦋 Changeset detected

Latest commit: 9373a7e

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

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-svelte-16721-svelte.vercel.app/

[github-actions]

Playground

pnpm add https://pkg.pr.new/svelte@16721

[dummdidumm]

Ah cool, thanks for starting that! Somewhat related I investigate various inconsistencies around the first run in #16709 and was thinking to add that on top, since it touches adjacent code paths (the PR already fixes the "properly run attachments and other effects created non-sync" part, but not the top level effects part). But I'll hold off from doing that since this looks promising.

[Ocean-OS]

This has been superseded by #16738, closing this.