Version 0.2.0 - Major refactoring release

Major Changes:
- Unified life.F90 module combining phytoplankton and zooplankton
- Modular chemistry components (chlorophyll, detritus, nutrient, sink)
- Enhanced library functions (predation, flexible stoichiometry)
- Multi-group support with size-based food webs
- Improved CI/CD with GitHub Actions and GitLab CI
- 1D test setups and visualization tools
- REUSE compliance enforcement

Contributors: Carsten Lemmen, Kai Wirtz, Thomas Imbert