feat(reader): add reading comfort controls

[oldwinter]

Built a compact Aa reading-comfort control for article pages, with 90%, 100%, 110%, and 120% body-text sizes that persist locally and survive Quartz SPA navigation. It is worth merging because it makes long-form reading immediately more comfortable without changing the site's layout, metadata, code blocks, dependencies, or publishing configuration.

Validation

• npx tsx --test quartz/components/scripts/readingComfort.test.ts quartz/plugins/emitters/componentResources.test.ts quartz/components/renderPage.test.ts - 24/24 passed
• npx tsc --noEmit - passed
• Scoped npx prettier --check ... - passed
• npx quartz build - passed; 314 Markdown inputs emitted 1,911 files
• Real Chrome QA at 1280px and 320px verified persistence, SPA navigation, keyboard/focus behavior, dark mode, reduced motion, storage failure handling, and cross-tab updates
• Mobile QA verified a 36px gap between the open panel and article content with zero horizontal overflow
• Full npm test run: 226/227 passed; the remaining existing theme-switcher test cannot resolve the undeclared jsdom package

Impact

• Adds one reader action, one small popover, localized labels for English and Simplified/Traditional Chinese, and a reading-comfort local-storage preference
• Scales only the central article body and headings; metadata, navigation, toolbars, sidebars, code, and page width stay unchanged
• Adds no dependencies and does not touch content, deployment, CI, configuration, permissions, or infrastructure

Rollback

Revert commit b1cccf1879b729914deac7e3fed77fd3deb27f09. The only persisted state is the harmless reading-comfort local-storage key.

Known baseline warnings

The production build still reports the repository's existing generated-plugin eval warning, one invalid content date, and a Google Fonts HTTP 400 warning for LXGW WenKai.

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[netlify]

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Name	Link
🔨 Latest commit	b1cccf1
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[oldwinter]

Blocking review at exact head b1cccf1879b729914deac7e3fed77fd3deb27f09:

• Direct article H1 headings do not scale: the later .page article > h1 { font-size: 2rem; } wins the equal-specificity cascade.
• Inline code does scale with the article despite the PR claim that code stays unchanged.
• ReadingComfort reaches into ReadLater markup/state directly, coupling two controls; DOM/storage/reset/focus behavior is not executed by tests.

Unblock action: rebase onto current v5, fix computed CSS for headings and inline code, decouple sibling disclosure state, and add real computed-style/browser regressions.