test(perf): verify route-profile stylesheets load [Codex]

[jderochervlk]

Part of #1371.

The route-profile direct-load suite previously established that stylesheet links were rendered, but a broken stylesheet URL could still pass that check.

Each profile now fetches every emitted stylesheet after loading and requires a successful response before asserting the route content. This verifies deployed CSS availability across the documented route families and control pages without adding timing-sensitive assertions.

[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-22T13:33:18.423150Z	6b16b0e	New commits

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[github-actions]

Lighthouse route profiles

Compared with target branch test/route-profile-media-dimensions at commit 127490a. Every score is the median of the deployed preview runs for that route.

Route	Performance	Accessibility	Best practices	SEO
/	84 -> 84 (0)	80 -> 80 (0)	100 -> 100 (0)	58 -> 58 (0)
/docs/manual/introduction	78 -> 78 (0)	78 -> 78 (0)	100 -> 100 (0)	50 -> 50 (0)
/docs/manual/api/stdlib/array	80 -> 79 (-1)	77 -> 77 (0)	100 -> 100 (0)	50 -> 50 (0)
/blog	77 -> 78 (+1)	80 -> 80 (0)	100 -> 100 (0)	50 -> 50 (0)
/blog/reactive-analysis	84 -> 85 (+1)	78 -> 78 (0)	100 -> 100 (0)	50 -> 50 (0)
/community/overview	83 -> 84 (+1)	85 -> 85 (0)	100 -> 100 (0)	58 -> 58 (0)
/packages	75 -> 76 (+1)	86 -> 86 (0)	96 -> 96 (0)	45 -> 45 (0)
/syntax-lookup	84 -> 83 (-1)	83 -> 83 (0)	100 -> 100 (0)	58 -> 58 (0)
/try	25 -> 24 (-1)	86 -> 86 (0)	96 -> 96 (0)	92 -> 92 (0)
/brand	85 -> 87 (+2)	83 -> 83 (0)	100 -> 100 (0)	54 -> 54 (0)
/__route-profile-not-found	96 -> 91 (-5)	82 -> 82 (0)	100 -> 100 (0)	42 -> 42 (0)

Download the full Lighthouse reports and baselines

_{Commit f334a10}

[github-actions]

Docs preview