- LanguageContext: new schoolLanguage + setSchoolLanguage
- LanguageDropdown: two tabs (Muttersprache / Schulsprache) with flag selection
- UnitBuilder: defaults target language to schoolLanguage
- Stored in bp_school_language localStorage (default: de)
- Shows school flag badge next to main language when different
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>