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>

sonar-project.properties

@@ -13,7 +13,7 @@ sonar.eslint.reportPaths=eslint-report.json
 sonar.docker.hadolint.reportPaths=hadolint-dev.json,hadolint-prod.json
 sonar.dependencyCheck.jsonReportPath=dependency-check-report.json
 sonar.dependencyCheck.htmlReportPath=dependency-check-report.html
-sonar.cpd.exclusions=templates/pdf/**
+sonar.cpd.exclusions=templates/pdf/**,src/Entity/**
 sonar.issue.ignore.multicriteria=e1,e2,e3,e4,e5,e6,e7,e8
 sonar.issue.ignore.multicriteria.e6.ruleKey=Web:S5725
 sonar.issue.ignore.multicriteria.e6.resourceKey=templates/order/payment.html.twig