Major changes:
- Renamed package from lego_image_converter to legopic
- New modular architecture with core/, data/, models/ subpackages
- Perceptual color matching using CIEDE2000 algorithm
- Canvas model for Lego mosaic representation
- Palette support with LEGO color database
- Session-based workflow for image processing
- Comprehensive test suite (89% coverage)
- Modern Python packaging with pyproject.toml
- Type hints throughout (py.typed)
- GitHub Actions CI/CD with Codecov integration