Add Walkthrough Mode card to main menu

index.html

@@ -653,6 +653,13 @@
                     <div class="category-count">5 Fun Activities</div>
                 </div>
 
+                <div class="category-card walkthrough" onclick="showCategory('walkthrough')">
+                    <div class="category-icon">🎓</div>
+                    <h3 class="category-title">Walkthrough Mode</h3>
+                    <p class="category-description">Learn step-by-step how neural networks work with interactive tutorials and explanations.</p>
+                    <div class="category-count">Guided Learning</div>
+                </div>
+
                 <div class="category-card developer" onclick="showCategory('developer')">
                     <div class="category-icon">⚙️</div>
                     <h3 class="category-title">Developer</h3>