Move presentation link from ecosystem to documentation section

docs/index.html

@@ -71,6 +71,9 @@ <h2>Documentation by intent</h2>
           <td><a href="reference/">Reference</a><br>Exact technical behavior, config, and interfaces.</td>
         </tr>
       </table>
+      <div style="margin-top: 1.5rem; padding: 1.25rem; background: var(--surface-2); border-left: 4px solid var(--brand); border-radius: 8px;">
+        <p style="margin-top: 0;"><strong>Quick visual overview:</strong> <a href="./deck/">View the 33-slide presentation deck</a> for an interactive walkthrough of GNAT's architecture, ecosystem, and capabilities.</p>
+      </div>
     </section>
 
     <section>
@@ -109,12 +112,6 @@ <h3>GNAT-gui</h3>
           <p>Browser-based analyst workbench — manage investigations, review evidence graphs, run gap analysis, draft reports, and monitor jobs with live streaming progress.</p>
           <a class="card-link card-link-gui" href="https://github.com/wrhalpin/GNAT-gui">Learn more</a>
         </div>
-        <div class="card card-deck">
-          <span class="card-tag">Presentation</span>
-          <h3>GNAT Deck</h3>
-          <p>Live browser-based presentation — platform overview, architecture, ecosystem map, and workflow, built with Reveal.js in the GNAT theme.</p>
-          <a class="card-link card-link-deck" href="./deck/">View deck</a>
-        </div>
       </div>
     </section>