Add slide 10: Configuration as Code definition

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

index.html

@@ -114,6 +114,13 @@
     <p><em>Yes, even your AI assistant can write it. But you still need to understand what it deploys.</em></p>
   </section>
 
+  <!-- ─── SLIDE 10 ──────────────────────────────────────────────────── -->
+  <section>
+    <h2>Configuration as Code</h2>
+    <p>Managing infrastructure through machine-readable files, stored in version control.</p>
+    <p style="margin-top:0.8em; color:#aaa;">Reproducible &nbsp;·&nbsp; Versionable &nbsp;·&nbsp; Auditable</p>
+  </section>
+
 
 </div>
 </div>