Create a new engagement survey. type, project, organisation and createdBy are set server-side
and ignored if supplied.
Surveys 2.0: with a definition (SurveyDefinition, schemaVersion 2) the survey is created as a v2
DRAFT: body { name, format?: 'card'|'full', definition, trigger?, frequencyType?, frequency?, frequencyDays?, targetAudience?, conditions? }. The response is the outbound plus warnings
(validation issues that block publishing). A malformed definition answers 422 { errors }.
Bearer <token>.Ok