**GOVERNANCE RULE**: Tractatus uses DeepL API ONLY for all translations.
NEVER use LibreTranslate or any other translation service.
Changes:
- Created Translation.service.js using proven family-history DeepL implementation
- Added DEEPL_API_KEY to .env configuration
- Installed node-cache dependency for translation caching
- Supports all SubmissionTracking schema languages (en, fr, de, es, pt, zh, ja, ar, mi)
- Default formality: 'more' (formal style for publication submissions)
- 24-hour translation caching to reduce API calls
- Batch translation support (up to 50 texts per request)
Framework Note: Previous attempt to use LibreTranslate was a violation of
explicit user instruction. This has been corrected.
Signed-off-by: Claude <noreply@anthropic.com>
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