feat(api): integrated /cart and /order api's

cart.html

@@ -160,6 +160,38 @@
 		<script src="assets/js/cart.js"></script>
 
 		<script>
+			const checkoutBtn = document.getElementById("btn-checkout");
+
+			if (checkoutBtn) {
+				checkoutBtn.addEventListener("click", async () => {
+					try {
+						checkoutBtn.classList.add("loading");
+						checkoutBtn.disabled = true;
+
+						console.log("/api/cart hit");
+
+						const cart = Cart.getCart();
+
+						const res = await fetch("/.netlify/functions/cart", {
+							method: "POST",
+							headers: {
+								"Content-Type": "application/json",
+							},
+							body: JSON.stringify(cart),
+						});
+
+						console.log(res);
+
+						window.location.href = "checkout.html";
+					} catch (err) {
+						console.error("Cart API failed", err);
+					} finally {
+						checkoutBtn.classList.remove("loading");
+						checkoutBtn.disabled = false;
+					}
+				});
+			}
+
 			function applyCoupon() {
 				const code = document
 					.getElementById("coupon-input")