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/sat_test.go

@@ -14,12 +14,12 @@ import (
 func TestStorageSATCommands(t *testing.T) {
 	t.Parallel()
 
-	nvme := storageSATCommands("/dev/nvme0n1")
+	nvme := storageSATCommands("/dev/nvme0n1", false)
 	if len(nvme) != 3 || nvme[2].cmd[0] != "nvme" {
 		t.Fatalf("unexpected nvme commands: %#v", nvme)
 	}
 
-	sata := storageSATCommands("/dev/sda")
+	sata := storageSATCommands("/dev/sda", false)
 	if len(sata) != 2 || sata[0].cmd[0] != "smartctl" {
 		t.Fatalf("unexpected sata commands: %#v", sata)
 	}