Fix: use Supabase auth.get_user() for ES256 JWT verification

Add Supabase auth + per-user sessions/flashcards

Fix: accept HEAD requests on /api/health for UptimeRobot

Update developer bio with accurate info

Add eduai-by-srk.vercel.app to CORS whitelist

Fix: runtime model download, writable /tmp paths, reduced context for free tier

Deploy EduAI backend - LLM + TTS + RAG + 15 maths chapters