feat(webui): combined GPU charts (load/memload/power/temp all GPUs per chart)

Replace per-GPU cards with 4 combined charts showing all GPUs as
separate series. Add gpu-all-load/memload/power/temp endpoints.

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

audit/internal/webui/server.go

@@ -449,7 +449,80 @@ func (h *handler) handleMetricsChartSVG(w http.ResponseWriter, r *http.Request)
 		yMin = floatPtr(0)
 		yMax = autoMax120(datasets...)
 
-	// ── GPU sub-charts ────────────────────────────────────────────────────
+	// ── Combined GPU charts (all GPUs on one chart) ───────────────────────
+	case path == "gpu-all-load":
+		title = "GPU Compute Load"
+		h.ringsMu.Lock()
+		for idx, gr := range h.gpuRings {
+			if gr == nil {
+				continue
+			}
+			vUtil, l := gr.Util.snapshot()
+			datasets = append(datasets, vUtil)
+			names = append(names, fmt.Sprintf("GPU %d %%", idx))
+			if len(labels) == 0 {
+				labels = l
+			}
+		}
+		h.ringsMu.Unlock()
+		yMin = floatPtr(0)
+		yMax = floatPtr(100)
+
+	case path == "gpu-all-memload":
+		title = "GPU Memory Load"
+		h.ringsMu.Lock()
+		for idx, gr := range h.gpuRings {
+			if gr == nil {
+				continue
+			}
+			vMem, l := gr.MemUtil.snapshot()
+			datasets = append(datasets, vMem)
+			names = append(names, fmt.Sprintf("GPU %d %%", idx))
+			if len(labels) == 0 {
+				labels = l
+			}
+		}
+		h.ringsMu.Unlock()
+		yMin = floatPtr(0)
+		yMax = floatPtr(100)
+
+	case path == "gpu-all-power":
+		title = "GPU Power"
+		h.ringsMu.Lock()
+		for idx, gr := range h.gpuRings {
+			if gr == nil {
+				continue
+			}
+			vPow, l := gr.Power.snapshot()
+			datasets = append(datasets, vPow)
+			names = append(names, fmt.Sprintf("GPU %d W", idx))
+			if len(labels) == 0 {
+				labels = l
+			}
+		}
+		h.ringsMu.Unlock()
+		yMin = floatPtr(0)
+		yMax = autoMax120(datasets...)
+
+	case path == "gpu-all-temp":
+		title = "GPU Temperature"
+		h.ringsMu.Lock()
+		for idx, gr := range h.gpuRings {
+			if gr == nil {
+				continue
+			}
+			vTemp, l := gr.Temp.snapshot()
+			datasets = append(datasets, vTemp)
+			names = append(names, fmt.Sprintf("GPU %d °C", idx))
+			if len(labels) == 0 {
+				labels = l
+			}
+		}
+		h.ringsMu.Unlock()
+		yMin = floatPtr(0)
+		yMax = autoMax120(datasets...)
+
+	// ── Per-GPU sub-charts ────────────────────────────────────────────────
 	case strings.HasPrefix(path, "gpu/"):
 		rest := strings.TrimPrefix(path, "gpu/")
 		// rest is either "{idx}-load", "{idx}-temp", "{idx}-power", or legacy "{idx}"