feat(docs): add prettier-plugin-bootstrap for automatic class sorting

[pierluigilenoci]

Summary

Adds prettier-plugin-bootstrap as a standalone npm package to automatically sort Bootstrap CSS classes following the framework's recommended order — similar to what prettier-plugin-tailwindcss provides for Tailwind CSS.

This addresses the feedback from #42359 where @coliff and @julien-deramond suggested extracting the plugin into a separate package.

Closes #38397

What changed

1. package.json — adds prettier-plugin-bootstrap@^0.2.1 as a dev dependency
2. site/.prettierrc.json — extends the existing plugins array with "prettier-plugin-bootstrap" (consolidated on the existing line per @coliff's review)
3. 28 .astro files — class attributes reordered by prettier --write (no functional changes)

Plugin features (v0.2.x)

• Sorts classes following Bootstrap's architecture (layout → components → helpers → utilities)
• Responsive variants (d-md-flex) sort immediately after their base class
• Unknown/custom classes preserved in their original relative order at the end
• bootstrapFunctions option for sorting inside clsx(), cn(), classNames() calls
• Supports HTML, JSX/TSX, Vue, Angular, Svelte, and Astro parsers
• 88 tests, 100% code coverage
• Zero runtime dependencies

Sorting order

1. Layout — containers, grid, columns
2. Components — btn, card, modal, navbar, etc. (following bootstrap.scss import order)
3. Helpers — clearfix, visually-hidden, stretched-link
4. Utilities — following the key order of scss/_utilities.scss

Plugin repository

https://github.com/pierluigilenoci/prettier-plugin-bootstrap

Test plan

• npx prettier --config site/.prettierrc.json -c site passes
• Plugin tested with HTML, JSX/TSX, Vue, Angular, Svelte, and Astro parsers
• 88 unit + integration + snapshot tests in the plugin repository
• 100% code coverage (statements, branches, functions, lines)
• CI green on Node 20/22
• Zero security vulnerabilities (Snyk verified)

[pierluigilenoci]

cc @julien-deramond @mdo @coliff — this adds automatic Bootstrap class sorting to the docs site via a Prettier plugin (similar to prettier-plugin-tailwindcss). Happy to adjust anything if needed.

[pierluigilenoci]

Update: addressed @coliff's review — consolidated the plugins array on a single line in site/.prettierrc.json (the previous version had a duplicate plugins key, which is now removed). Also refreshed the PR description: the dependency on #42389 is no longer relevant since #42390 (which enabled prettier-plugin-astro upstream) was merged. All CI green ✅, branch is up-to-date with main. Ready for another look whenever convenient — thanks!