refactor: harden diagnostics and consolidate runtime code

audit/internal/webui/metrics_charts_http.go

@@ -400,37 +400,6 @@ func normalizePowerSeries(ds []float64) []float64 {
 	return out
 }
 
-// psuSlotsFromSamples returns the sorted list of PSU slot numbers seen across samples.
-func psuSlotsFromSamples(samples []platform.LiveMetricSample) []int {
-	seen := map[int]struct{}{}
-	for _, s := range samples {
-		for _, p := range s.PSUs {
-			seen[p.Slot] = struct{}{}
-		}
-	}
-	slots := make([]int, 0, len(seen))
-	for s := range seen {
-		slots = append(slots, s)
-	}
-	sort.Ints(slots)
-	return slots
-}
-
-// psuStackedTotal returns the point-by-point sum of all PSU datasets (for scale calculation).
-func psuStackedTotal(datasets [][]float64) []float64 {
-	if len(datasets) == 0 {
-		return nil
-	}
-	n := len(datasets[0])
-	total := make([]float64, n)
-	for _, ds := range datasets {
-		for i, v := range ds {
-			total[i] += v
-		}
-	}
-	return total
-}
-
 func normalizeFanSeries(ds []float64) []float64 {
 	if len(ds) == 0 {
 		return nil