refactor: hand-authored pi-flow post + consolidated agents.md

- pi-flow-native-brain is now hand-authored HTML (direct SVGs + styled
  tables; no build.js passthrough needed)
- Card hardcoded in _index_template.html above {{CARDS}}
- Removed posts/pi-flow-native-brain.md (build.js no longer touches it)
- New agents.md: consolidated agent guide for the blog repo
  (blog architecture, build pipeline, adding posts, styling rules,
  writing guide, deploy instructions, skills reference)
- Removed old skills/blog.md (content migrated to agents.md)

index.html

@@ -120,6 +120,13 @@
 
   <!-- BLOG LIST -->
   <div class="blog-list">
+    <!-- hand-authored HTML posts (not from build.js) -->
+    <a href="pi-flow-native-brain" class="blog-card">
+      <span class="blog-card__date">3 June 2026</span>
+      <h2 class="blog-card__title">How Pi Agents Build, Test, and Ship Game Code with Oracle-Backed Flows</h2>
+      <p class="blog-card__excerpt">When we ask Pi to build a game feature, it doesn't just write code. It compiles, runs tests, drives the live game, measures feel, fixes CI failures, and ships a green PR — all through composable oracle-backed flows.</p>
+      <span class="blog-card__read">Read &rarr;</span>
+    </a>
 
     <a href="blog-visual-upgrade" class="blog-card">
       <span class="blog-card__date">3 June 2026</span>
@@ -128,13 +135,6 @@
       <span class="blog-card__read">Read &rarr;</span>
     </a>
 
-    <a href="pi-flow-native-brain" class="blog-card">
-      <span class="blog-card__date">3 June 2026</span>
-      <h2 class="blog-card__title">Pi's Flow-Native Brain: Retiring the Supervisor, Teaching Agents to Fix Their Own Builds</h2>
-      <p class="blog-card__excerpt">Two changes made Pi genuinely autonomous: we deleted the hardcoded supervisor and replaced it with composable oracle-backed flows, and we taught agents to watch CI, read failure logs, and fix their own broken builds.</p>
-      <span class="blog-card__read">Read &rarr;</span>
-    </a>
-
     <a href="cloud-harness" class="blog-card">
       <span class="blog-card__date">26 May 2026</span>
       <h2 class="blog-card__title">Building a Cloud Agent Harness with DeepSeek V4 and Pi</h2>