[+] cross-distro package mapping with fixtures and coverage tests
1. add package_mapping.py with package_map_t class;
2. supports: direct match, known aliases, version-aware (gcc-12, python3.11),
suffix strip (-libs, -utils, -doc), prefix strip (lib32-, lib-),
language prefixes (python->bare/py3-, perl->lib*-perl, ruby, haskell),
family packages (libreoffice-, firefox-, gst-, vlc-, qemu-, vim-);
3. lazy-initialized alias tables via _ensure_aliases classmethod;
4. tested_ecosystems set for honest supported count;
5. add distro package list fixtures: debian12, debian13, alpine321, wolfi, arch_latest;
6. add test_package_mapping.py with unit tests and coverage thresholds:
debian12>=50%, debian13>=50%, alpine>=8%, wolfi>=14%;