Correct validate task name to visual-baseline

[coneilen]

Summary

Correct #793. It told lanes to run validate.ps1 -Task windows-spikes, but no such task exists: windows-spikes is a CI workflow job. The task that runs the palette-parity contract is visual-baseline. Lane B2 caught the mistake.

Changes

• investigation/windows-parity-orchestration-plan.md: the per-PR gate now names -Task visual-baseline (VisualBaseline.Tests.ps1 plus PaletteParity.Tests.ps1). It states that windows-spikes is a CI job, and that every exact-head workflow must be green before merge.

Test plan

RED: Select-String Tools\windows\validate.ps1 ValidateSet on main 1e48374 -> no windows-spikes task exists; the plan named one
GREEN: validate.ps1 lines 1004-1015 -> the visual-baseline task runs VisualBaseline.Tests.ps1 and PaletteParity.Tests.ps1 with a nonzero-count guard; plan now names -Task visual-baseline
REGRESSION: git diff --check -> clean; git ls-files --eol -> CRLF preserved; bash Tools/ci/tests/classify-changes.test.sh -> 59 passed, 0 failed

Documentation-only change: no product code, so the Windows suites and macOS make test/make check were not run.

Checklist

• I have read the Contributing Guidelines
• I have signed off my commits (git commit -s) per the DCO
• Tests pass locally (make test)
• Code follows the existing style (make check)
• I added the test/contract before the implementation and observed the intended RED failure