87a2f93edb
Introduce user registration/login gated behind optional NEXT_PUBLIC_SUPABASE_* env vars (leave blank to disable — app behaves exactly as before). Adds proxy.ts for automatic cookie session refresh, requireUser() API route guards on all 7 compute-consuming routes, AuthModal (Google/GitHub OAuth + 6-digit email OTP), UserChip header component, and login_success analytics event. Identity is fully decoupled from Session/engine — no type changes. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>