post: blog visual upgrade — restyle story + toolkit guide

New public post documenting the blog's visual refresh:
- Design inspiration from internal team guide
- The three-layer styling architecture (site CSS → inline overrides)
- Full post template changes (gradient titles, code panels, pills, h2 bars)
- Index template changes (kicker, card hover, date pills)
- The build system (posts/*.md + templates → *.html via build.js)
- Comprehensive toolkit guide: adding posts, understanding templates,
  styling workflow, markdown dialect, extending build.js, cheatsheet

index.html

@@ -121,10 +121,10 @@
   <!-- BLOG LIST -->
   <div class="blog-list">
 
-    <a href="pi-flow-native-brain" class="blog-card">
+    <a href="blog-visual-upgrade" class="blog-card">
       <span class="blog-card__date">3 June 2026</span>
-      <h2 class="blog-card__title">Retiring the Supervisor: Pi's Flow-Native Brain</h2>
-      <p class="blog-card__excerpt">We deleted 1,050 lines of hardcoded supervisor logic and replaced it with oracle-backed pi-flows. The verify_build oracle now powers a gate-based pipeline that agents compose dynamically.</p>
+      <h2 class="blog-card__title">Our Blog Just Got a Visual Upgrade — Here's How We Did It</h2>
+      <p class="blog-card__excerpt">We gave the Tinqs blog a visual refresh — borrowing the dark, gradient-heavy look from our internal team docs. Here's why, what we changed, and how the build system made it painless.</p>
       <span class="blog-card__read">Read &rarr;</span>
     </a>