[site] Upgrade docusaurus and other depencies

[the-other-tim-brown]

What is the purpose of the pull request

Resolves over 100 issues reported by Dependabot due to our dependencies

Brief change log

Dependency upgrade — package.json + package-lock.json

• @docusaurus/core, @docusaurus/preset-classic, @docusaurus/module-type-aliases: 3.0.0 → 3.10.2
• clsx ^1.2.1 → ^2.0.0, prism-react-renderer ^1.3.5 → ^2.3.0
• engines.node: >=16.14 → >=20.0 (matches CI's Node 20)
• New overrides: serialize-javascript ^7.0.5, uuid ^11.1.1, brace-expansion ^5.0.8 — all three required; without them the lockfile carries 24 advisories
• Lockfile regenerated → npm audit reports 0 vulnerabilities (was 121 open Dependabot alerts)

Required API migrations for 3.10

• docusaurus.config.js: prism-react-renderer/themes/* → const {themes: prismThemes} = require('prism-react-renderer'); top-level onBrokenMarkdownLinks → markdown.hooks.onBrokenMarkdownLinks
• 7 files under src/theme/BlogPostItem/: useBlogPost import moved from @docusaurus/theme-common/internal → @docusaurus/plugin-content-blog/client. No logic touched — the customizations (50%-width cards, no sidebar, date-only info) are unchanged

Webflow root pages — moved out of static/

• static/index.html → homepage/index.html and static/404.html → homepage/404.html (git renames)
• docusaurus.config.js: new inline postBuild plugin (xtable-webflow-root-pages) copies homepage/ into the build root after Docusaurus writes its output

Two reasons, both verified: in static/, index.html collides with webpack's own asset in dev (Conflict: Multiple assets emit different content… → Reload prevented, hot reload dead); and on 3.10 the generated 404.html overwrites the static one, which would have silently dropped the Webflow 404 that's live today. This replaced the last session's NODE_ENV-conditional staticDirectories, which fixed only the first problem.

README.md

The "Changes to the website homepage" section now describes website/homepage/ as the home of the hand-written Webflow root pages, how they reach the build, why they aren't in static/, and that previewing the homepage needs npm run build && npm run serve rather than npm start.

Net: 10 files modified (+58/−17 excluding the lockfile), 2 file renames, plus the regenerated lockfile. docs/ and blog/ are untouched — the files I edited during hot-reload probing were restored.

Verify this pull request

Ran site locally to ensure pages still render as they did before