fix: initialize files bind on hydration

[paoloricciuti]

Closes #15054

No test because i'm not sure how we could test this if you have ideas I can implement them 😄

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[changeset-bot]

🦋 Changeset detected

Latest commit: a65d463

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Playground

pnpm add https://pkg.pr.new/svelte@15059

[Rich-Harris]

preview: https://svelte-dev-git-preview-svelte-15059-svelte.vercel.app/

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