chore: use unbundled type declarations for @sveltejs/kit/* modules

[Rich-Harris]

We use dts-buddy to bundle our types, but the original reason for doing so doesn't really apply any more, as far as the @sveltejs/kit/* modules go — everyone uses a modern moduleResolution option now (I think the legacy ones were removed or deprecated?) which means types resolve conditions in package.exports are reliable. So we don't need to use declare module for people to be able to see the types of subpackages.

We do still need it for $app/* modules, of course. But making this change speeds up prepublishOnly, and means that cmd-click works much more reliably (no sourcemaps between you and the code).

One thing I'm not sure about is why the RequestEvent and Cookies types are being inlined into $app/server rather than imported from @sveltejs/kit. Not sure off the top of my head if that's a bug in dts-buddy or a missing piece of config or something.

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[pkg-svelte-dev]

Install the latest version of @sveltejs/kit from 4e1b22c:

pnpm add https://pkg.svelte.dev/@sveltejs/kit/c/4e1b22cbcdce6deb7ba1fed6c21872a3e62a6342

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/kit/pr/16775

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🦋 Changeset detected

Latest commit: 4e1b22c

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

This PR includes changesets to release 1 package

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@sveltejs/kit	Patch

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[teemingc]

We might also need to avoid importing internal files/types in those public.d.ts files. They cause type checking to check more files than they should and they conflict either due to missing tsconfig.json settings (paths: { types: ... }) or clashing ambient types. This wasn't an issue before because the type bundling would extract them without leaving any references back to the original files (which is what we're trying to do... hmm)