chore(main): release 2.9.0

[mdn-bot]

🤖 I have created a release beep boop

2.9.0 (2026-09-04)

Features

• baseline: implement new banner design (#1821) (ba04401)
• index: style index navigation links (#1827) (ac0a394)
• observatory: show COEP and COOP results in scoring (#1843) (9f5469b)
• sandbox: add per-component preview routes (2219bc6)

Bug Fixes

• baseline: add <code> styling to discouraged reason (#1852) (82f41e7)
• baseline: add lang attribute to discouraged reason (#1853) (09e5bf0)
• button: make disabled state more obvious (#1825) (cadedeb)
• search-modal: add ARIA combobox semantics to quick search (#1706) (23c02d4)

Miscellaneous

• baseline: add sandbox component (#1820) (0327ed5)
• deps: bump @codemirror/state from 6.7.1 to 6.7.2 in the npm-prod group (#1837) (03bee6c)
• deps: bump @codemirror/state in the npm-prod group (03bee6c)
• deps: bump fflate from 0.8.2 to 0.8.3 (#1854) (ba3c1d4)
• deps: bump js-yaml from 4.1.1 to 4.3.2 (#1851) (022ed57)
• deps: bump postcss-selector-parser from 6.1.2 to 6.1.4 (#1841) (15c4a53)
• deps: bump shell-quote and concurrently (#1816) (bfc255f)
• sandbox: pass context to sandbox components (#1819) (f794093)
• sandbox: use import.meta.webpackContext (#1818) (4ae04ea)
• test: support filtering spec files (#1848) (0e0569e)

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1c180f4 was deployed to: https://fred-pr1817.review.mdn.allizom.net/