Public preview endpoint for onboarding flow - no authentication required. Shows potential language partners: native speakers and fellow learners of the target language. Prioritizes users with profile pictures and recent activity.

DELIBERATELY STILL PUBLIC: its only caller is /onboarding/preview/partners, a pre-signup route (listed in App.jsx publicRoutes) that anonymous visitors reach from the onboarding flow — requiring auth would break the funnel.

But it is now DE-IDENTIFIED. It used to publish, to anyone on the internet, a language-filterable directory of real members: user id, username, full name, photo, bio, location and last-active time. Cards now carry only a first name, the language pair, and a rough last-active time — enough social proof for the preview, not a scrapeable member list. The id is a random per-response value (the page uses it only as a React key) so a card can't be cross-referenced against /users/profile/{id} or any other endpoint.