- Add comprehensive implementation plan for universal sync system
- Update README with API reference and device setup guides
- Add KOBO_SETUP.md device configuration guide
- Add SECURITY_AUDIT.md with A- security rating
- Add SECURITY_ENHANCEMENTS.md for improvements
- Add DEVICE_CAP_IMPLEMENTATION.md complete guide
- Add KOREADER_SETUP.md device setup guide
- Add SYNC_USER_GUIDE.md user documentation
- Document all API endpoints and features
- Include security considerations and best practices