Sweep site quality, accessibility, dependencies, and CI

[plx]

Summary

• fix duplicate/incorrect primary metadata, normalize Markdown out of social/RSS metadata, honor noOgImage, and make content dates timezone-stable
• fix deterministic back navigation, reduced-motion scrolling, hidden focus, mobile inline-code overflow, heading levels, contrast, social-link names, and scrollable-code landmarks
• restore real Astro accessibility linting, fail closed on malformed category metadata, factor shared social/OG logic, and remove unused React/icon/SEO/template code
• refresh safe dependencies and the Node 24 patch, eliminate all npm audit findings, pin GitHub Actions, tighten workflow permissions, and add Dependabot
• expand unit and Playwright coverage across metadata, RSS, dates, categories, themes, focus/navigation, axe scans, browser errors, and every sitemap route at narrow widths
• run Chromium QA in CI with a deterministic static preview server, while also restoring Markdown linting to the required gate

The rendered body text remains unchanged across all 24 generated HTML pages. The only visual differences are targeted bug fixes: wrapping overflowing inline code and small contrast corrections.

Validation

• npm ci — clean install; 0 vulnerabilities
• npm run validate:all — 46 unit tests, 24-page Astro build with 0 diagnostics, spelling/prose/Markdown/link/feed validation, and 50 Chromium browser tests
• Chromium/WebKit/Mobile Safari axe coverage in light and dark modes
• all sitemap routes checked at 320px and 375px with zero document overflow
• actionlint
• zizmor .github/workflows --pedantic — no findings
• just --fmt --check
• rendered-body comparison against the pre-change build — unchanged on all 24 HTML pages

TypeScript 7, Tailwind 4, tailwind-merge 3, and Node 26 type definitions remain deliberately deferred as separate major migrations; the watch items are documented in planning/major-migration-plan.md.

Closes #42

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-08-30T22:47:23.455856Z	9ab2fc0	PR opened

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