- vite.config.ts: proxy target via VITE_API_TARGET env var (falls back to localhost)
- docker-compose.dev.yml: set VITE_API_TARGET=http://backend:8000
- Add /login-success and /register-success placeholder pages
- Show real API error messages in login/register forms
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>