Run CleanupSubscriberIntegrationsService before delete: remove coupon code
in Weeztix via list+DELETE API; update Mailwizz contact to strip configured
source tag from the tag field and clear the mapped coupon field.
Extract MailwizzCheckboxlistTags and MailwizzSubscriberFormPayload for
shared sync/cleanup behaviour. Add WeeztixService list and delete helpers.
Integration failures are logged only; local delete always proceeds.
Feature tests cover Mailwizz strip+clear and Weeztix delete paths.
Made-with: Cursor
