Drop xunit.runner.console — redundant with Microsoft.NET.Test.Sdk

[ChrisonSimtian]

build/_build.csproj declares <PackageDownload Include="xunit.runner.console" Version="[2.6.1]" />. We run tests via dotnet test which uses Microsoft.NET.Test.Sdk + the per-project xunit.runner.visualstudio adapter. The standalone xunit.runner.console is for the older non-dotnet-test invocation path.

Confirm unused, drop.

Refs the dependency audit. Done when:

• grep -r 'xunit.runner.console' src tests build — only the package download declaration left
• PackageDownload removed
• ./build.ps1 Test still passes

[ChrisonSimtian]

Partially resolved in 97ea857. The original "redundant with Microsoft.NET.Test.Sdk" assessment was true for actual test runs — we don't invoke xunit.console.dll directly — but Fallout.Tooling.Tests.ToolTasksToolPathTest uses xunit.runner.console as a sample package for tool-path resolution smoke tests (NuGetToolPathResolver walks the local cache for that ID). The PackageDownload stays in build/_build.csproj with an explanatory comment. Closing since the original goal (no runtime dependency, no waste in CI on tool-runner mechanics we don't use) is met.