- Add src/auth.rs with require_auth middleware extracting user_id from Bearer token
- Wire auth middleware onto all /api/* routes
- Replace CorsLayer::permissive() with env-driven FRONTEND_URL/ADMIN_URL origins
- Pass real auth_user.user_id to confirm_action instead of conversation_id
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>