#6: computed News read-time + per-page OG/canonical for hub detail pages

- News card "3 min read" → computed from our own gist (~200 wpm, floor 1). We
  summarize, so it's honestly ~"1 min read" — the good news in about a minute.
- Generalized the build-time head patch (patch-play-head → patch-static-heads):
  now also rewrites build/word.html, quote.html, onthisday.html so each ships
  its own <title>/description/canonical/OG/Twitter tags instead of the homepage
  head + canonical="/". Non-JS scrapers and canonical dedup are correct before
  these pages are ever un-noindexed. Same fail-loud guard as before.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/routes/home3/+page.svelte

@@ -26,6 +26,11 @@
   // truncation handled by CSS (-webkit-line-clamp:2) — breaks on whole words, fills 2 full lines
   let headline = $derived(news?.title ?? 'What went right this week: the good news that actually matters');
 
+  // Honest read-time from our own gist (~200 wpm, floor 1). We summarize, so this is
+  // usually "1 min read" — a feature, not a bug: the good news in about a minute.
+  const readMins = (t) => Math.max(1, Math.round((t || '').trim().split(/\s+/).filter(Boolean).length / 200));
+  let readTime = $derived(`${readMins(news?.summary)} min read`);
+
   // small-joys shelf: 3 cells shown two at a time, rotated by the reader (no auto-motion)
   const JOY_ACCENTS = ['#4f7da8', '#b06a86', '#b06a45'];
   let joyIdx = $state(0);
@@ -125,7 +130,7 @@
           <p class="summary">{news?.summary || "We read the week so you don't have to doomscroll it. Five quietly hopeful stories, summarised to the gist."}</p>
         </a>
         <div class="news-foot">
-          <span class="meta">3 min read</span>
+          <span class="meta">{readTime}</span>
         </div>
         <hr class="news-div" />
         <a class="news-more" href="/">Read more good news →</a>