fix: remove manual transaction creation causing 400 error

- Remove CREATE_TRANSACTION_MUTATION call that's causing 400 error
- Saleor's checkoutComplete already creates order with NOT_CHARGED status for COD
- Order doesn't need manual transaction - staff handles fulfillment in dashboard
- Keep payment method selection and UI components intact

src/app/[locale]/checkout/page.tsx

@@ -19,7 +19,6 @@ import {
   CHECKOUT_METADATA_UPDATE,
   CHECKOUT_SHIPPING_METHOD_UPDATE,
 } from "@/lib/saleor/mutations/Checkout";
-import { CREATE_TRANSACTION_MUTATION } from "@/lib/saleor/payments/cod";
 import { PaymentSection } from "./components/PaymentSection";
 import { DEFAULT_PAYMENT_METHOD } from "@/lib/config/paymentMethods";
 import { GET_CHECKOUT_BY_ID } from "@/lib/saleor/queries/Checkout";
@@ -386,37 +385,6 @@ export default function CheckoutPage() {
         const order = completeResult.data?.checkoutComplete?.order;
         if (order) {
           setOrderNumber(order.number);
-          
-          // Create COD transaction for the order
-          if (selectedPaymentMethod === 'cod') {
-            console.log("Step 6: Creating COD transaction...");
-            try {
-              await saleorClient.mutate({
-                mutation: CREATE_TRANSACTION_MUTATION,
-                variables: {
-                  id: order.id,
-                  transaction: {
-                    name: "Cash on Delivery",
-                    pspReference: `COD-${order.number}-${Date.now()}`,
-                    availableActions: ["CHARGE"],
-                    amountAuthorized: {
-                      amount: 0,
-                      currency: "RSD"
-                    },
-                    amountCharged: {
-                      amount: 0,
-                      currency: "RSD"
-                    }
-                  }
-                }
-              });
-              console.log("Step 6: COD transaction created successfully");
-            } catch (txError) {
-              console.error("Failed to create COD transaction:", txError);
-              // Don't fail the order if transaction creation fails
-            }
-          }
-          
           setOrderComplete(true);
           
           // Track order completion