create-svelte: Make hooks file comply with TypeScript strictest mode

[KuSh]

Fixes:

• Error: Module '@types/cookie/index' has no default export. ts(1192)
• Error: Property 'userid' comes from an index signature, so it must be accessed with ['userid']. ts(4111)

Strictest tsconfig from https://github.com/tsconfig/bases/blob/27f9097a02f960e351d69bca8dd4c7581d70e1b6/bases/strictest.json

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[changeset-bot]

🦋 Changeset detected

Latest commit: 3b2bce2

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

This PR includes changesets to release 1 package

Name	Type
create-svelte	Patch

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[Rich-Harris]

thanks!