chore(deps): upgrade dependencies for Astro 7 (DOCSDEV-75)

[Infi-Knight]

Phase 2a of DOCSDEV-75. This site is the Astro 7 canary for the docs fleet.

Dependency changes

• astro 6.3.8 to 7.2.10
• @astrojs/starlight 0.39.2 to 0.42.0
• @astrojs/markdown-remark added at 7.3.0
• @interledger/docs-design-system 0.13.0 to 0.14.0
• starlight-links-validator 0.24.0 to 0.26.0
• sharp 0.34.5 to 0.35.4
• eslint 10.4.0 to 10.9.1
• eslint-plugin-astro 1.7.0 to 3.1.0
• astro-eslint-parser 1.4.0 to 3.1.0
• typescript-eslint and @typescript-eslint/parser 8.60.0 to 8.69.0
• globals 17.6.0 to 17.11.0
• prettier 3.8.3 to 3.9.6
• eslint-plugin-jsx-a11y added at 6.10.2

The exact pins on astro, @astrojs/starlight and @interledger/docs-design-system are kept, because this site is the canary.

Markdown processor

Astro 7 makes Sätteri the default markdown processor. Sätteri does not run remark or rehype plugins, and Starlight follows the same default.

This cycle keeps every Starlight site on the unified() processor, so all sites stay on the pipeline they run today. Three sites in the fleet depend on remark and rehype plugins, and the Sätteri ports of those plugins are 0.1.x packages with roughly 25 downloads per week. Astro documents both processors as officially supported and states they provide identical built-in features by default.

This site configures no plugins, so its unified() call takes no arguments.

Accessibility rules

eslint-plugin-astro 3 exposes accessibility rule sets that version 1 did not. The config now extends flat/jsx-a11y-recommended, which turns on 31 rules. This site reports 0 findings.

bun install prints one stale peer warning for eslint-plugin-jsx-a11y, which declares eslint ^3 to ^9 but runs correctly on ESLint 10. bun has no peerDependencyRules equivalent, so the warning stays. It is expected and not a real problem.

Canary findings for the rest of the cycle

These answered open questions for the other repos.

compressHTML needs no override. Astro 7 changes the default from true to "jsx", which alters whitespace between inline elements. I extracted the rendered text of /syntax/, /security/ and /iana/ and compared each against the live production page. All three are identical. No override is needed anywhere in the fleet.

The Rust compiler rejected nothing. No markup needed fixing.

Starlight 0.42.0 is safe for this fleet. It landed during this cycle and simplifies the mobile menu markup, which can break component overrides and custom styles. No repo in the fleet targets starlight-menu-button, MobileMenuToggle, PageFrame, or uses the removed tagline option. Starlight 0.42 also moves to @astrojs/mdx ^8 and @astrojs/markdown-satteri ^0.4, which removed a version conflict present on 0.41.

Test plan

• bun install clean, only the known stale jsx-a11y peer warning
• bun run build passed, 8 pages
• starlight-links-validator 0.26.0 reports all internal links valid
• Pagefind index built, 8 HTML files
• bun run lint exits 0 at --max-warnings=0
• 0 accessibility findings with the 31 new rules active
• Rendered text identical to production on 3 pages
• @interledger/docs-design-system bumped to 0.14.0 and rebuilt (commit 99198d9)
• Test deployment CI passing
• Deploy preview spot-checked by a reviewer

Refs: DOCSDEV-75