- Add organizer fields to User entity: companyName, siret, address, postalCode, city, phone - Update RegistrationController to handle buyer and organizer registration types - Create register template with tab selector (acheteur/organisateur) - Organizer registration assigns ROLE_ORGANIZER - Add migration for new User fields Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>