Release 1.3.0

- Add generic mapping constructors to Column API for flexible type transformations
- Support custom transformations from any input type to any output type
- Enable simplified syntax for common conversion patterns (enums, conditional logic, formatting)

- Enhanced Column API flexibility while maintaining backward compatibility
- Better support for complex data transformations in Excel generation

- Simplified column declarations for type conversions
- Comprehensive test coverage for new mapping constructors
- Fixed compiler warnings in test suite