bump typescript

[Rich-Harris]

#7654. We also need to

• [ ] update the TS conversion for the docs to use satisfies (in this PR, or in a follow-up?)
• [ ] use satisfies in the template

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Latest commit: d7c8a6f7086afc783473aa2484d8544ae7072d82

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[Rich-Harris]

Couple of blockers:

• adapter-vercel no longer typechecks. wtf?
• Sucrase, which we use to strip TypeScript out of the template source files, does not know how to deal with the satisfies operator

[benmccann]

I filed an issue in the sucrase repo: https://github.com/alangpierce/sucrase/issues/763. It's now been addressed

[dummdidumm]

Re "use satisfies in the docs" - I would maybe wait 1-2 months before doing that, so people can familiarize themselves more with that. Also, VS Code is likely not on TS 4.9 yet so everyone not turning on "use TS workspace version" would see type errors and be confused.

[dummdidumm]

Another blocker: prettier doesn't support that syntax yet. ESLint likely, too?

[dummdidumm]

Aside: It would be great if this https://github.com/microsoft/TypeScript/issues/51086 was implemented, too - then JSDoc could also use that, and we don't need to create proxy types anymore for both JS/TS when people use it.

[dummdidumm]

Bummer, function foo () {} satisfies Bar is invalid syntax, so we need to keep using const foo = (() => {}) satisfies Bar instead. Opened #51556

[benmccann]

Prettier was updated in the 2.8 release (https://github.com/prettier/prettier/issues/13792), which master now uses

@typescript-eslint/parser was addressed in 5.45.0 (https://github.com/typescript-eslint/typescript-eslint/issues/5688). This repo doesn't use that project, but users are now unblocked

[benmccann]

master is now using TypeScript 4.9, so most of this PR is obsolete. I'm going to close it in favor of https://github.com/sveltejs/kit/pull/7861, which extracts out the parts that haven't already been committed to master