Benchmark: parallel GPU mode, resilient inventory query, server model in results

- Add parallel GPU mode (checkbox, off by default): runs all selected GPUs
  simultaneously via a single bee-gpu-burn invocation instead of sequentially;
  per-GPU telemetry, throttle counters, TOPS, and scoring are preserved
- Make queryBenchmarkGPUInfo resilient: falls back to a base field set when
  extended fields (attribute.multiprocessor_count, power.default_limit) cause
  exit status 2, preventing lgc normalization from being silently skipped
- Log explicit "graphics clock lock skipped" note when inventory is unavailable
- Collect server model from DMI (/sys/class/dmi/id/product_name) and store in
  result JSON; benchmark history columns now show "Server Model (N× GPU Model)"
  grouped by server+GPU type rather than individual GPU index

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

audit/internal/webui/api.go

@@ -470,6 +470,7 @@ func (h *handler) handleAPIBenchmarkNvidiaRun(w http.ResponseWriter, r *http.Req
 		GPUIndices        []int  `json:"gpu_indices"`
 		ExcludeGPUIndices []int  `json:"exclude_gpu_indices"`
 		RunNCCL           *bool  `json:"run_nccl"`
+		ParallelGPUs      *bool  `json:"parallel_gpus"`
 		DisplayName       string `json:"display_name"`
 	}
 	if r.Body != nil {
@@ -483,6 +484,10 @@ func (h *handler) handleAPIBenchmarkNvidiaRun(w http.ResponseWriter, r *http.Req
 	if body.RunNCCL != nil {
 		runNCCL = *body.RunNCCL
 	}
+	parallelGPUs := false
+	if body.ParallelGPUs != nil {
+		parallelGPUs = *body.ParallelGPUs
+	}
 	name := taskDisplayName("nvidia-benchmark", "", "")
 	if strings.TrimSpace(body.DisplayName) != "" {
 		name = body.DisplayName
@@ -493,6 +498,7 @@ func (h *handler) handleAPIBenchmarkNvidiaRun(w http.ResponseWriter, r *http.Req
 		SizeMB:            body.SizeMB,
 		BenchmarkProfile:  body.Profile,
 		RunNCCL:           runNCCL,
+		ParallelGPUs:      parallelGPUs,
 		DisplayName:       body.DisplayName,
 	}, name, h.opts.App, "benchmark-nvidia")
 	if err != nil {