fix: clear Mailwizz checkboxlist tag when deleting subscriber

Encode empty checkboxlist arrays as an empty scalar so multipart requests
include the field. On delete, PUT only coupon and tag fields to Mailwizz
after merging the tag CSV from getSubscriber.

Made-with: Cursor

app/Services/CleanupSubscriberIntegrationsService.php

@@ -104,8 +104,8 @@ final class CleanupSubscriberIntegrationsService
         }
 
         $subscriberUid = $search['subscriber_uid'];
-        $phoneEnabled = $page->isPhoneFieldEnabledForSubscribers();
-        $data = MailwizzSubscriberFormPayload::baseFields($subscriber, $config, $phoneEnabled);
+        /** @var array<string, mixed> $data */
+        $data = [];
 
         $couponField = $config->field_coupon_code;
         if (is_string($couponField) && $couponField !== '') {
@@ -123,6 +123,10 @@ final class CleanupSubscriberIntegrationsService
             $data[$tagField] = MailwizzCheckboxlistTags::removeValueFromCsv($existingCsv, $tagValue);
         }
 
+        if ($data === []) {
+            return;
+        }
+
         $service->updateSubscriber($listUid, $subscriberUid, $data);
     }