build: rename package from ekglib to ekg-lib for PyPI

- Rename GitHub repository from ekglib to ekg-lib
- Rename source directory from src/ekglib to src/ekg_lib
- Update all imports from ekglib to ekg_lib
- Update pyproject.toml package name and URLs
- Add GitHub Actions workflow for PyPI publishing with trusted publishing
- Update README with PyPI installation instructions
- Add FUNDING.yml for GitHub sponsors
- Update all references in docs, tests, and workflows

BREAKING CHANGE: Package import changed from `import ekglib` to
`import ekg_lib`

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

chore(version): bump version to 0.0.28