[verification] MR !83 deployment acceptance — authenticated widget SSO

Verification record for MR !83 / issue #706. Posted from the production console at admin.wodex.ai via the authenticated Quackback widget. Confirms: server-signed HS256 SSO token accepted under hmacRequired, identity resolved (greeting and Posting-as both show the signed-in user), widget iframe rendered and submission path works end to end. Not a real feature request.