add qr code section to course index pages

scripts/generate-index.sh

@@ -166,6 +166,23 @@ cat > "$BUILD_DIR/index.html" << HEADER
     }
     footer a { color: $ACCENT_COLOR; text-decoration: none; }
     footer a:hover { text-decoration: underline; }
+    .qr-section {
+      margin-top: 2.5rem;
+      padding: 1.5rem;
+      background: #fff;
+      border-radius: 12px;
+      box-shadow: 0 1px 3px rgba(0,0,0,0.08);
+      text-align: center;
+    }
+    .qr-code {
+      width: 100%;
+      height: auto;
+    }
+    .qr-url {
+      margin-top: 0.75rem;
+      font-size: 0.85rem;
+      color: #86868b;
+    }
     @media (max-width: 600px) {
       .termin-card {
         grid-template-columns: 1fr;
@@ -240,6 +257,10 @@ done
 
 cat >> "$BUILD_DIR/index.html" << FOOTER
   </div>
+  <div class="qr-section">
+    <img src="qr-index.svg" alt="QR Code" class="qr-code">
+    <p class="qr-url">$SLIDES_URL</p>
+  </div>
   <footer>
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