[WIP] Add Node runtime preflight check for self-hosted and GPU workflows

[Copilot]

• Inspect relevant self-hosted/GPU runtime setup paths and workflow history for the recurring Node runtime failure
• Run baseline build/tests for the affected workflow/runtime code paths
• Add a fast-fail Node 22+ preflight in the setup/bootstrap path used by self-hosted and GPU runners
• Add focused regression coverage for the new preflight behavior
• Run targeted validation, repo-required checks, secret scan, and final review