fix(ci) : set APP_ENV=prod in production Dockerfile

Without APP_ENV=prod, Symfony defaults to dev and tries to load
DoctrineFixturesBundle which is excluded by --no-dev.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

infra/prod/Dockerfile

@@ -58,6 +58,8 @@ RUN curl --insecure https://getcomposer.org/composer.phar -o /usr/bin/composer &
 
 WORKDIR /var/www/html
 
+ENV APP_ENV=prod
+
 # Copier les fichiers projet
 COPY . /var/www/html