Two 18.x installs coexisted: VS2026 Community (full IDE, has VC v180)
and a BuildTools at (x86)\Microsoft Visual Studio\18\BuildTools that
has MSBuild but NO VC v180 targets. The vswhere query only required
Microsoft.Component.MSBuild, so -latest could (and did) return the
C++-less BuildTools -> MSB4019. Also require
Microsoft.VisualStudio.Component.VC.Tools.x86.x64 so only installs
with the C++ toolset match; the broken BuildTools is excluded and
2026\Community is selected. CI VM BuildTools has the C++ workload so
it still matches.