Exhaustive search technology

There have been some recent advances in exhaustive searches. Consider how these can be used as an alternative to the leaps package:

- [lmSubsets](https://cran.r-project.org/web/packages/lmSubsets/index.html)
- [COMBSS: best subset selection via continuous optimization](https://link.springer.com/article/10.1007/s11222-024-10387-8)