fix(iso): restore boot UX and boot logs

audit/internal/webui/server.go

@@ -690,7 +690,7 @@ func chartDataFromSamples(path string, samples []platform.LiveMetricSample) (dat
 		// Use per-PSU stacked chart when PSU SDR data is available.
 		// Collect the union of PSU slots seen across all samples.
 		psuSlots := psuSlotsFromSamples(samples)
-		if len(psuSlots) > 1 {
+		if len(psuSlots) > 0 {
 			// Build one dataset per PSU slot.
 			psuDatasets := make([][]float64, len(psuSlots))
 			psuNames := make([]string, len(psuSlots))
@@ -709,7 +709,7 @@ func chartDataFromSamples(path string, samples []platform.LiveMetricSample) (dat
 			}
 			datasets = psuDatasets
 			names = psuNames
-			stacked = true
+			stacked = len(psuDatasets) > 0
 			yMax = autoMax120(psuStackedTotal(psuDatasets))
 		} else {
 			power := make([]float64, len(samples))