MSBuild/NuGet/CPM architecture validator. MUST be triggered:(1) Before committing changes to .props, .targets, .csproj, nuget.config, global.json(2) When user runs /lint-dotnet(3) After ANY MSBuild-related file editCatches: hardcoded versions, duplicate imports, CPM bypass, single-owner violations.Prevents CI failures by validating locally before push.