feat: auto-login after checkout via page reload

Changed Checkout page order success handling:
- Before: SPA navigate() to thank-you page (cookies not refreshed)
- After: window.location.href + reload (cookies refreshed)

This ensures guests who are auto-registered during checkout
get their auth cookies properly set after order placement.

customer-spa/src/pages/Checkout/index.tsx

@@ -241,7 +241,12 @@ export default function Checkout() {
         useCartStore.getState().clearCart();
 
         toast.success('Order placed successfully!');
-        navigate(`/order-received/${data.order_id}?key=${data.order_key}`);
+
+        // Use full page reload instead of SPA routing
+        // This ensures auto-registered users get their auth cookies properly set
+        const thankYouUrl = `${window.location.origin}/store/#/order-received/${data.order_id}?key=${data.order_key}`;
+        window.location.href = thankYouUrl;
+        window.location.reload();
       } else {
         throw new Error(data.error || 'Failed to create order');
       }