Refactor validate modes, fix benchmark report and IPMI power

- Replace diag level 1-4 dropdown with Validate/Stress radio buttons
- Validate: dcgmi L2, 60s CPU, 256MB/1p memtester, SMART short
- Stress: dcgmi L3 + targeted_stress in Run All, 30min CPU, 1GB/3p memtester, SMART long/NVMe extended
- Parallel GPU mode: spawn single task for all GPUs instead of splitting per model
- Benchmark table: per-GPU columns for sequential runs, server-wide column for parallel
- Benchmark report converted to Markdown with server model, GPU model, version in header; only steady-state charts
- Fix IPMI power parsing in benchmark (was looking for 'Current Power', correct field is 'Instantaneous power reading')

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

audit/internal/platform/benchmark.go

@@ -326,8 +326,8 @@ func (s *System) RunNvidiaBenchmark(ctx context.Context, baseDir string, opts Nv
 	}
 
 	report := renderBenchmarkReportWithCharts(result, loadBenchmarkReportCharts(runDir, selected))
-	if err := os.WriteFile(filepath.Join(runDir, "report.txt"), []byte(report), 0644); err != nil {
-		return "", fmt.Errorf("write report.txt: %w", err)
+	if err := os.WriteFile(filepath.Join(runDir, "report.md"), []byte(report), 0644); err != nil {
+		return "", fmt.Errorf("write report.md: %w", err)
 	}
 
 	summary := renderBenchmarkSummary(result)
@@ -1183,18 +1183,8 @@ func queryIPMIServerPowerW() (float64, error) {
 	if err != nil {
 		return 0, fmt.Errorf("ipmitool dcmi power reading: %w", err)
 	}
-	for _, line := range strings.Split(string(out), "\n") {
-		if strings.Contains(line, "Current Power") {
-			parts := strings.SplitN(line, ":", 2)
-			if len(parts) == 2 {
-				val := strings.TrimSpace(strings.TrimSuffix(strings.TrimSpace(parts[1]), "Watts"))
-				val = strings.TrimSpace(val)
-				w, err := strconv.ParseFloat(val, 64)
-				if err == nil && w > 0 {
-					return w, nil
-				}
-			}
-		}
+	if w := parseDCMIPowerReading(string(out)); w > 0 {
+		return w, nil
 	}
 	return 0, fmt.Errorf("could not parse ipmitool dcmi power reading output")
 }