- Remove /languparent prefix from all API calls (routes are at /auth/* now)
- Align register/login token handling (JWT returned directly, no registration token)
- Feed rewritten to use new getFeedPairs endpoint with PairSentenceCard/YesNoCard/WordCard
- App.jsx: check language_native_id / language_target_id for profile completeness
- Profil.jsx: add logout button
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>