Group archived files by archive unit in find_undeclared_files instead
of reporting individual ROMs. Add path-based fallback for descriptive
names (e.g. "SeaBIOS (128 KB)" resolves via path: bios.bin). Update
_collect_extras to use archive name for pack resolution. Regenerate
database with new bios files. 6 new E2E tests covering archive
in_repo, missing archives, descriptive names, and pack extras.