- Add complete test coverage for referenzen, rollen, and stichworte apps
- Implement 54 new tests covering models, relationships, and business logic
- Fix MPTT method names and import issues in test implementations
- Create comprehensive test documentation in English and German
- All 188 tests now passing across all Django apps
Test coverage breakdown:
- referenzen: 18 tests (MPTT hierarchy, model validation)
- rollen: 18 tests (role models, relationships)
- stichworte: 18 tests (keyword models, ordering)
- Total: 54 new tests added
Documentation:
- Test suite.md: Complete English documentation
- Test Suite-DE.md: Complete German documentation
