Add scalability/ramp-up labeling, ServerPower penalty in scoring, and report improvements

- Add RampStep/RampTotal/RampRunID to NvidiaBenchmarkOptions, taskParams, and
  NvidiaBenchmarkResult so ramp-up steps can be correlated across result.json files
- Add ScalabilityScore field to NvidiaBenchmarkResult (placeholder; computed externally
  by comparing ramp-up step results sharing the same ramp_run_id)
- Propagate ramp fields through api.go (generates shared ramp_run_id at spawn time),
  tasks.go handler, and benchmark.go result population
- Apply ServerPower penalty to CompositeScore when IPMI reporting_ratio < 0.75:
  factor = ratio/0.75, applied per-GPU with a note explaining the reduction
- Add finding when server power delta exceeds GPU-reported sum by >25% (non-GPU draw)
- Report header now shows ramp step N/M and run ID instead of "parallel" when in ramp mode;
  shows scalability_score when non-zero

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

audit/internal/platform/benchmark.go

@@ -109,6 +109,9 @@ func (s *System) RunNvidiaBenchmark(ctx context.Context, baseDir string, opts Nv
 		ServerModel:        readServerModel(),
 		BenchmarkProfile:   spec.Name,
 		ParallelGPUs:       opts.ParallelGPUs,
+		RampStep:           opts.RampStep,
+		RampTotal:          opts.RampTotal,
+		RampRunID:          opts.RampRunID,
 		SelectedGPUIndices: append([]int(nil), selected...),
 		HostConfig:         readBenchmarkHostConfig(),
 		Normalization: BenchmarkNormalization{
@@ -344,6 +347,20 @@ func (s *System) RunNvidiaBenchmark(ctx context.Context, baseDir string, opts Nv
 	}
 	result.ServerPower = characterizeServerPower(serverIdleW, serverLoadedW, gpuReportedSumW, serverIdleOK && serverLoadedOK)
 
+	// Apply server-power penalty when IPMI reports the server delta is much
+	// lower than GPU-reported sum: GPU power telemetry is over-stated, making
+	// CalibratedPeakPowerW and PowerSustainScore unreliable.
+	// Penalty factor scales from 1.0 (ratio ≥ 0.75, no penalty) down to 0.
+	if sp := result.ServerPower; sp != nil && sp.Available && sp.ReportingRatio > 0 && sp.ReportingRatio < 0.75 {
+		factor := sp.ReportingRatio / 0.75
+		for i := range result.GPUs {
+			result.GPUs[i].Scores.CompositeScore *= factor
+			result.GPUs[i].Notes = append(result.GPUs[i].Notes,
+				fmt.Sprintf("server-power penalty applied (reporting_ratio=%.2f < 0.75): composite score reduced to %.1f%%",
+					sp.ReportingRatio, factor*100))
+		}
+	}
+
 	result.Findings = buildBenchmarkFindings(result)
 	result.OverallStatus = benchmarkOverallStatus(result)
 
@@ -1178,9 +1195,14 @@ func buildBenchmarkFindings(result NvidiaBenchmarkResult) []string {
 	if sp := result.ServerPower; sp != nil && sp.Available && sp.GPUReportedSumW > 0 {
 		if sp.ReportingRatio < 0.75 {
 			findings = append(findings, fmt.Sprintf(
-				"GPU power reporting may be unreliable: server delta %.0f W vs GPU-reported %.0f W (ratio %.2f). GPU telemetry likely over-reports actual consumption.",
+				"GPU power reporting may be unreliable: server delta %.0f W vs GPU-reported %.0f W (ratio %.2f). GPU telemetry likely over-reports actual consumption. Composite scores have been penalized accordingly.",
 				sp.DeltaW, sp.GPUReportedSumW, sp.ReportingRatio,
 			))
+		} else if sp.ReportingRatio > 1.25 {
+			findings = append(findings, fmt.Sprintf(
+				"Server power delta %.0f W exceeds GPU-reported sum %.0f W by %.0f%%. Other components (CPU, NVMe, networking) may be drawing substantial power under GPU load.",
+				sp.DeltaW, sp.GPUReportedSumW, (sp.ReportingRatio-1)*100,
+			))
 		}
 	}
 	return dedupeStrings(findings)