estructura inicial de carrito hecha

src/main/resources/static/assets/js/pages/imprimelibros/cart-badge.js

@@ -0,0 +1,28 @@
+$(() => {
+    const badge = document.getElementById("cart-item-count");
+    if (!badge) return;
+
+    function updateCartCount() {
+        fetch("/cart/count")
+            .then(res => res.ok ? res.text() : "0")
+            .then(count => {
+                const n = parseInt(count || "0", 10);
+                if (isNaN(n) || n === 0) {
+                    badge.classList.add("d-none");
+                } else {
+                    badge.textContent = n;
+                    badge.classList.remove("d-none");
+                }
+            })
+            .catch(() => badge.classList.add("d-none"));
+    }
+
+    // Actualizar al cargar
+    updateCartCount();
+
+    // Si quieres refrescar cada 60s:
+    setInterval(updateCartCount, 60000);
+
+    // generate a custom event to update the cart count from other scripts
+    document.addEventListener("update-cart", updateCartCount);
+});