cleave & Scan v2.5.0: quiet failures get loud, and cleave lands on Windows

Files that used to produce no verdict at all — a truncated archive, a half-written gzip, a member that failed to scan — now say so. Plus ISO analysis, verified Mach-O signatures, five seconds off every cold start, and first builds for Windows, DragonFlyBSD, NetBSD, illumos/OmniOS and Solaris 11.4.