fix(affiliate): persist referral code through SPA checkout and process after save

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

@@ -599,6 +599,18 @@ export default function Checkout() {
     setIsProcessing(true);
 
     try {
+      const referralCode = (() => {
+        try {
+          const stored = localStorage.getItem('woonoow_ref')?.trim();
+          if (stored) return stored;
+        } catch {
+          // Ignore storage access errors.
+        }
+
+        const match = document.cookie.match(/(?:^|;\s*)woonoow_ref=([^;]+)/);
+        return match ? decodeURIComponent(match[1]).trim() : '';
+      })();
+
       // Prepare order data
       const orderData = {
         items: cart.items.map(item => ({
@@ -652,6 +664,7 @@ export default function Checkout() {
         custom_fields: customFieldData,
         // CAPTCHA token for security validation
         captcha_token: captchaToken,
+        referral_code: referralCode || undefined,
       };
 
       // Submit order
@@ -670,8 +683,16 @@ export default function Checkout() {
         // If user was logged in during this request (guest auto-register), 
         // we need a full page reload to recognize the auth cookie
         if (data.user_logged_in) {
+          // Get basePath from window
+          const basePath = (window as any).woonoowCustomer?.basePath ?? '/store';
+          
+          // Ensure thankYouUrl starts with / if basePath doesn't end with /
+          const sep = basePath.endsWith('/') || thankYouUrl.startsWith('/') ? '' : '/';
+          const prefix = thankYouUrl.startsWith('/') && basePath.endsWith('/') ? basePath.slice(0, -1) : basePath;
+          
           // Full page reload so browser recognizes the new auth cookie
-          window.location.href = thankYouUrl;
+          const path = thankYouUrl.startsWith('/') ? thankYouUrl.slice(1) : thankYouUrl;
+          window.location.href = `${prefix}${sep}${path}`;
         } else {
           // Already logged in or no login happened - SPA navigate is fine
           navigate(thankYouUrl, { replace: true });