fix(osrelease): fix all merlint issues (E105/E400/E405/E605)
- Fix catch-all exception → Scanf.Scan_failure | Failure (E105)
- Add module documentation comment to osrelease.mli (E400)
- Add docs for all 20 public values in Arch, OS, Distro, Version (E405)
- Create test/test_osrelease.ml/mli, test.ml, dune (E605)