Astro 6 support

[HiDeoo]

Description

This PR adds support for Astro 6 (currently requires exactly version 6.0.0-beta.1)

This is an early draft, more details will be added over time, and preview releases will be published later too for testing purposes.

Known issues

Symbol	Status
🟢	Fixed
🟡	Fix pending review
🔴	No fix yet, under investigation

• 🟢 Build issue on Windows when importing an Astro component with a <script> in MDX using an import alias
  • Repro
  • Fixed by Fix windows build issue with import alias astro#15112
• 🟢 The Markdoc example is failing to build as an updated version of @astrojs/markdoc was not published as part of the alpha.
• 🔴 Incompatible with Vitest 4
  • Issue
• 🟢 SSR build issue with explicit URL imports, e.g. import styles from '../styles/custom.css?url&no-inline'
  • Repro
  • Fixed by Filter routes by environment and fix image loading astro#15093
• 🟡 Extra CSS emitted in dev depending on the order of visited pages
  • Repro
  • Should be fixed by Fix CSS collection in dev mode with content collections astro#15167
• 🟡 Adding CSS to a component that did not previously had CSS requires a restart of the dev server to take effect
  • Repro
  • Should be fixed by Fix CSS updates when adding/removing style tags astro#15133
• 🟢 SSR issue where visiting some pages matching pre-rendered route patterns can crash the server
  • Repro
  • Fixed by node: skip ssr for pre-rendered pages astro#15164
• 🔴 Typechecking error due to Ship Starlight using `.js` + `.d.ts` files #983 and the starlight-links-validator plugin not being updated for Zod 4 yet.

Remaining tasks

• Bump Netlify Node.js version to 22.12.0+.
• Fix links validation errors once all docs changes are validated.
  • Use Lunaria directives if needed when merging this PR
• Bump size-limit CSS size limit
  • Only did a really quick check, but it seems that some previously inlined CSS is now extracted to a separate file and linked in the HTML. The CSS is similar between Astro v5 and v6, and its size is around 7.4K. Vite default assetsInlineLimit value is 4K, so it makes sense that the CSS is not inlined and the current behavior seems correct. A great idea from Chris could be that it was previously considered several chunks, each under 4K, and now bundled together, but that would need to be verified.
• Bump some peer dependencies versions once ready to release.
• Search and address any TODO(HiDeoo) comments.
• Add changesets.

[changeset-bot]

⚠️ No Changeset found

Latest commit: 770105c

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.

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[netlify]

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[astrobot-houston]

Lunaria Status Overview

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Tracked Files

Locale	File	Note
en	guides/i18n.mdx	Source changed, localizations will be marked as outdated.
en	guides/sidebar.mdx	Source changed, localizations will be marked as outdated.
en	manual-setup.mdx	Source changed, localizations will be marked as outdated.
en	reference/frontmatter.md	Source changed, localizations will be marked as outdated.
en	reference/route-data.mdx	Source changed, localizations will be marked as outdated.

Warnings reference

Icon	Description
🔄️	The source for this localization has been updated since the creation of this pull request, make sure all changes in the source have been applied.

[delucis]

Exciting to see the working preview deploy! Awesome work @HiDeoo 👏