Sprint SPRINT_20260419_028_Tools_targeted_xunit_runner_workflow (TEST-RUNNER-001 DOING — sprint remains active). - scripts/test-targeted-xunit.ps1: rebuild-and-invoke xUnit v3 in-process runner directly so targeted filters work under Microsoft Testing Platform (dotnet test --filter is ignored there). - Register sprint file in implplan. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>