Add LibreTranslate auto-translation, improve test coverage, fix code duplication

Translation system:
- Add LibreTranslate container (dev + prod), CPU-only, no port exposed, FR/EN/ES/DE/IT
- Create app:translate command: reads *.fr.yaml, translates incrementally, preserves placeholders
- Makefile: make trans / make trans_prod (stops container after translation)
- Ansible: start libretranslate -> translate -> stop during deploy
- Prod container restart: "no" (only runs during deploy)
- .gitignore: ignore generated *.en/es/de/it.yaml files
- 11 tests for TranslateCommand (API unreachable, empty, incremental, obsolete keys, placeholders, fallback)

Test coverage improvements:
- OrderController: event ended (400), invalid cart JSON, invalid email, stock zero (4 new tests)
- AccountController: finance stats all statuses (paid/pending/refunded/cancelled), soldCounts (2 new tests)
- JS cart: checkout without error elements, hide error on retry, stock polling edge cases (singular, no label, qty zero, unknown billet) (8 new tests)
- JS editor: comment node sanitization (1 new test)
- JS tabs: missing panel, generated id, parent null, click no-panel (5 new tests)

Code duplication fixes:
- MeilisearchConsistencyCommand: extract diffAndReport() method (was duplicated 3x)
- Email templates: extract _order_items_table.html.twig partial (shared by notification + cancelled)
- SonarQube: exclude src/Entity/** from CPD (getters/setters duplication)

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

Makefile

@@ -93,6 +93,15 @@ pwa_dev: ## Compile les assets PWA en dev via Docker
 pwa_prod: ## Compile les assets PWA en prod via Docker
 	docker compose -f docker-compose-prod.yml exec php php bin/console pwa:compile --env=prod
 
+## —— Traductions ——————————————————————————————————
+trans: ## Traduit les fichiers YAML FR vers EN/ES/DE/IT via LibreTranslate (Docker dev)
+	docker compose -f docker-compose-dev.yml exec php php bin/console app:translate
+	docker compose -f docker-compose-dev.yml stop libretranslate
+
+trans_prod: ## Traduit les fichiers YAML FR vers EN/ES/DE/IT via LibreTranslate (Docker prod)
+	docker compose -f docker-compose-prod.yml exec -T php php bin/console app:translate --env=prod
+	docker compose -f docker-compose-prod.yml stop libretranslate
+
 ## —— Qualite ——————————————————————————————————————
 hadolint: ## Lance Hadolint sur les Dockerfiles
 	hadolint docker/php/dev/Dockerfile