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))

audit/internal/webui/server_test.go

@@ -420,6 +420,45 @@ func TestHandleMetricsChartSVGRendersCustomSVG(t *testing.T) {
 	}
 }
 
+func TestChartDataFromSamplesServerPowerUsesPerPSUDatasets(t *testing.T) {
+	start := time.Date(2026, 4, 5, 12, 0, 0, 0, time.UTC)
+	samples := []platform.LiveMetricSample{
+		{
+			Timestamp: start,
+			PSUs: []platform.PSUReading{
+				{Slot: 1, PowerW: 120},
+				{Slot: 2, PowerW: 130},
+			},
+			PowerW: 250,
+		},
+		{
+			Timestamp: start.Add(time.Minute),
+			PSUs: []platform.PSUReading{
+				{Slot: 1, PowerW: 140},
+				{Slot: 2, PowerW: 135},
+			},
+			PowerW: 275,
+		},
+	}
+
+	datasets, names, _, title, _, _, stacked, ok := chartDataFromSamples("server-power", samples)
+	if !ok {
+		t.Fatal("expected server-power chart data")
+	}
+	if title != "System Power" {
+		t.Fatalf("title=%q", title)
+	}
+	if !stacked {
+		t.Fatal("expected stacked PSU chart")
+	}
+	if len(datasets) != 2 || len(names) != 2 {
+		t.Fatalf("datasets=%d names=%d want 2/2", len(datasets), len(names))
+	}
+	if names[0] != "PSU 1" || names[1] != "PSU 2" {
+		t.Fatalf("names=%v", names)
+	}
+}
+
 func TestNormalizeFanSeriesHoldsLastPositive(t *testing.T) {
 	got := normalizeFanSeries([]float64{4200, 0, 0, 4300, 0})
 	want := []float64{4200, 4200, 4200, 4300, 4300}