Docusaurus: Update Docusaurus to 3.7

[clemyan]

What's the problem this PR addresses?

The Docusaurus version we use is not the latest

How did you fix it?

Upgrades Docusuaurs to 3.7 and start using the new features:

• Also upgrade docusaurus-plugin-typedoc-api for compatibility
  • docusaurus-plugin-typedoc-api is unmaintined now. Maybe we should make our custom solution eventually?
• Upgrade React to v19 since Docusuaurs 3.7 supports it now
  • Also upgrades other libraries for official compatibility with React 19, which, while maybe not strictly necessary (nothing seems to break without those upgrades), is nice to get out of the way
• Upgrade xterm so the website can be built with Node 22
• Bump the Netlify build to Node 22, as Node 18 will be EOL this week.
• Add truncation of blog posts on the main blog feed (recommended by Docusaurus)
• Add author social links to blog posts (@arcanis I just copied the socials from your website, expect replacing Twitter with BlueSky and adding the website itself. Please review if there are changes you'd like to make)
• Remove the extraneous dependencies that weren't removed in Minor tweaks to website #6264.
  • Now I'm pretty sure markdown-it-br and marked-base-url is actually usused
  • Even if we are to rebuild the sherlock playground, I feel like there are better libraries for that then @codesandbox/sandpack-react. Even if we use @codesandbox/sandpack-react again we'd probably use the latest version which is a semver-major bump so there will be churn either way.
• Minor fixes like fixing backgrounds

I have done some visual comparison testing to verify there aren't unexpected visual changes (on the pages I checked at least)

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Questions:

• Docusaurus's perf logger now records memory usage. Maybe we should turn that on on Netlify?
• Do we want to start migrating to compressionLevel: 0 (the default since 4.0)? This PR replaces ~300 deps (out of ~2,100) so I feel like that's a good time to do so if we are to migrate

Checklist

• I have read the Contributing Guide.

• I have set the packages that need to be released for my changes to be effective.

• I will check that all automated PR checks pass before the PR gets reviewed.