chore: update dev configs for vscode and eslint

[sacrosanctic]

Closes nothing

Description

• Remove eslint.useFlatConfig (no longer needed in ESLint v10)
• Remove typescript.tsdk from VSCode settings (causes TS errors in snapshots)

Checklist

• Update snapshots (if applicable)
• Add a changeset (if applicable)
• Allow maintainers to edit this PR
• I care about what I'm doing, no matter the tool I use (Notepad, Sublime, VSCode, AI...)

[changeset-bot]

⚠️ No Changeset found

Latest commit: 1a9fe09

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-cli-1017-svelte.vercel.app/

[pkg-pr-new]

Open in StackBlitz

npx https://pkg.pr.new/svelte-migrate@1017

npx https://pkg.pr.new/sv@1017

npx https://pkg.pr.new/@sveltejs/sv-utils@1017

commit: 1a9fe09