OptionaldisplayOptionalusernameOptionalisOptionallanguageLanguage the platform reports for the sender (BCP 47-ish code, e.g. 'en',
'pt-BR'), when it has one. Used by i18n language resolution; providers
that only expose it in platformData.languageCode work too.
Optionalplatform
Base, cross-transport sender fields only. WA-only vocabulary (phoneNumber, lid, isBusiness) and Telegram/Discord extras (languageCode, nickname, roles) live in
platformData, NOT as named fields on the shared type.