Fix ConfirmationButton usage in pricing page and e2e tests

- Update pricing page to use ConfirmationButton API correctly (isConfirming, onConfirm, onCancel, onActionClick)
- Fix e2e tests to set up response listeners before navigation
- Fix validation error selector to use .first() for multiple matches
- All 9 e2e tests now passing

frontend/app/admin/pricing/page.tsx

@@ -49,6 +49,7 @@ export default function AdminPricingPage() {
   const [errors, setErrors] = useState<ValidationErrors>({});
   const [error, setError] = useState<string | null>(null);
   const [success, setSuccess] = useState(false);
+  const [isConfirming, setIsConfirming] = useState(false);
 
   const fetchConfig = useCallback(async () => {
     setError(null);
@@ -180,12 +181,16 @@ export default function AdminPricingPage() {
     },
   });
 
-  const handleSave = () => {
-    if (!formData) return;
+  const handleConfirmSave = () => {
+    if (!formData) {
+      setIsConfirming(false);
+      return;
+    }
 
     const validationErrors = validateForm(formData);
     if (Object.keys(validationErrors).length > 0) {
       setErrors(validationErrors);
+      setIsConfirming(false);
       return;
     }
 
@@ -199,6 +204,7 @@ export default function AdminPricingPage() {
       eur_min_sell: formData.eur_min_sell,
       eur_max_sell: formData.eur_max_sell,
     });
+    setIsConfirming(false);
   };
 
   if (isLoading || !formData) {
@@ -385,16 +391,19 @@ export default function AdminPricingPage() {
 
           <div style={formStyles.actions}>
             <ConfirmationButton
-              onClick={handleSave}
-              disabled={hasErrors || isSaving}
-              confirmMessage={t("pricing.confirmSave")}
-              style={{
+              isConfirming={isConfirming}
+              onConfirm={handleConfirmSave}
+              onCancel={() => setIsConfirming(false)}
+              onActionClick={() => setIsConfirming(true)}
+              actionLabel={isSaving ? tCommon("saving") : t("pricing.save")}
+              confirmLabel={tCommon("confirm")}
+              cancelLabel={tCommon("cancel")}
+              isLoading={isSaving}
+              actionButtonStyle={{
                 ...buttonStyles.primary,
                 ...(hasErrors || isSaving ? buttonStyles.disabled : {}),
               }}
-            >
-              {isSaving ? tCommon("saving") : t("pricing.save")}
-            </ConfirmationButton>
+            />
           </div>
         </form>
       </div>