fix: update eslint-scope to v9

[Pixel998]

Prerequisites checklist

• I have read the contributing guidelines.

AI acknowledgment

• I did not use AI to generate this PR.
• (If the above is not checked) I have reviewed the AI-generated content before submitting.

What is the purpose of this pull request?

This PR upgrades eslint-scope to the latest version and removes the separate @types/eslint-scope dependency now that eslint-scope ships its own TypeScript declarations.

What changes did you make? (Give an overview)

• Upgraded eslint-scope from ^8.4.0 to ^9.1.2
• Removed @types/eslint-scope from devDependencies
• Removed a stale sourceType as never cast.

Related Issues

Is there anything you'd like reviewers to focus on?

[netlify]

✅ Deploy Preview for eslint-code-explorer ready!

Name	Link
🔨 Latest commit	e54fb29
🔍 Latest deploy log	https://app.netlify.com/projects/eslint-code-explorer/deploys/69dde00ee7f2df000803e2ae
😎 Deploy Preview	https://deploy-preview-285--eslint-code-explorer.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[github-actions]

Hi everyone, it looks like we lost track of this pull request. Please review and see what the next steps are. This pull request will auto-close in 7 days without an update.

[DMartens]

The new scope manager requires calling sourceCode.addGlobals to add builtin globals.
For example currently Object is not being resolved to a global.

[Pixel998]

Do you mean we should call scopeManager.addGlobals() (rather than sourceCode.addGlobals()) to add language globals? If so, that seems like a separate follow-up from the eslint-scope upgrade itself.