Complete Windows CI gate for pinned SimpleGraphic runtime

[rodgons]

Part of #1

Task

Complete the existing Windows Build DLL workflow for SimpleGraphic commit 98e98efcc747fea5ee96dd933de51685887db417, which is the exact runtime commit pinned by the first macOS RC.

The draft upstream validation PR is PathOfBuildingCommunity/PathOfBuilding-SimpleGraphic#107. Its exact-commit Actions run is https://github.com/PathOfBuildingCommunity/PathOfBuilding-SimpleGraphic/actions/runs/30608752617 and currently requires upstream maintainer approval.

Acceptance criteria

• An upstream maintainer approves the external-contributor workflow run.
• .github/workflows/main.yml completes successfully on Windows for the exact pinned commit.
• The successful run ID is recorded on Validate the macOS release candidate artifact #12 and supplied to the macOS release workflow.

This blocks publication of the immutable macOS RC artifact.