Update an attachment

Updates an attachment. Set its type via type — either a predefined type ({ name }) or a custom, tenant-defined type ({ id }) — and/or update expiryDate and validFrom. Fields that are omitted are left unchanged; pass null for a date to clear it. The type must be allowed for all records the attachment is linked to: the predefined CV type can only be set on attachments linked to a candidate, and custom types define which record types they support. Attachments with platform-internal types are treated as not found.