chore: sync upstream — performance, webmentions v2, OG v3
- _data: switch to cachedFetch wrapper (10s timeout + 4h watch cache)
- js/webmentions.js: owner reply threading, platform provenance badges, DOM dedup, Micropub reply support
- js/comments.js: owner detection, reply system, Alpine.store integration
- _includes/components/webmentions.njk: data-wm-* attrs, provenance badge slots, reply buttons
- _includes/components/comments.njk: owner-aware comment form, threaded replies
- widgets/toc.njk: Alpine.js tocScanner upgrade (replaces is-land/inline-JS)
- lib/og.js + og-cli.js: OG card v3 (light theme, avatar, batched spawn, DESIGN_VERSION=3)
- eleventy.config.js: hasOgImage cache, memoized date filters, batched OG/unfurl, post-build GC, YouTube check opt
- base.njk: Inter font preloads + toc-scanner.js script
- critical.css: font-face declarations (font-display:optional)
- tailwind.css: font-display swap→optional
- tailwind.config.js: prose link colors -700→-600
- Color design system: accent-700/300 → accent-600/400 across components
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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