Phase 1.1 — user_language_api.py: Stores native language preference
per user (TR/AR/UK/RU/PL/DE/EN). Onboarding page with flag-based
language selection for students and parents.
Phase 1.2 — translation_service.py: Batch-translates vocabulary words
into target languages via Ollama LLM. Stores in translations JSONB.
New endpoint POST /vocabulary/translate triggers translation.
Phase 2.1 — Parent Portal (/parent): Simplified UI in parent's native
language showing child's learning progress. Daily tips translated.
Phase 2.2 — Parent Quiz (/parent/quiz/[unitId]): Parents can quiz
their child on vocabulary WITHOUT speaking DE or EN. Shows word in
child's learning language + parent's native language as hint.
Answer hidden by default, revealed on tap.
All UI text translated into 7 languages (DE/EN/TR/AR/UK/RU/PL).
Arabic gets RTL layout support.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>