WS-F.4: phantom-GPU normalization helper (blocked on PR #275)

Part of epic tracebloc/backend#1106. Full spec: report §5 (mirrored on the epic; artifact https://claude.ai/code/artifact/b4b6e6a6-4d76-4e46-a668-6f4f0f944344). WS-F.4: after #275 merges, centralize the hand-copied normalization as resources.NormalizeAgainstNode(...). Chart-side source fix raised separately in the client repo. BLOCKED until #275 lands.