feat: CPU SAT via stress-ng + BMC version via ipmitool

BMC:
- collector/board.go: collectBMCFirmware() via ipmitool mc info, graceful skip if /dev/ipmi0 absent
- collector/collector.go: append BMC firmware record to snap.Firmware
- app/panel.go: show BMC version in TUI right-panel header alongside BIOS

CPU SAT:
- platform/sat.go: RunCPUAcceptancePack(baseDir, durationSec) — lscpu + sensors before/after + stress-ng
- app/app.go: RunCPUAcceptancePack + RunCPUAcceptancePackResult methods, satRunner interface updated
- app/panel.go: CPU row now reads real PASS/FAIL from cpu-*/summary.txt via satStatuses(); cpuDetailResult shows last SAT summary + audit data
- tui/types.go: actionRunCPUSAT, confirmBody for CPU test with mode label
- tui/screen_health_check.go: hcCPUDurations [60,300,900]s; hcRunSingle(CPU)→confirm screen; executeRunAll uses RunCPUAcceptancePackResult
- tui/forms.go: actionRunCPUSAT → RunCPUAcceptancePackResult with mode duration
- cmd/bee/main.go: bee sat cpu [--duration N] subcommand

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

audit/internal/tui/forms.go

@@ -92,6 +92,13 @@ func (m model) updateConfirm(msg tea.KeyMsg) (tea.Model, tea.Cmd) {
 				result, err := m.app.RunStorageAcceptancePackResult("")
 				return resultMsg{title: result.Title, body: result.Body, err: err, back: screenHealthCheck}
 			}
+		case actionRunCPUSAT:
+			m.busyTitle = "CPU test"
+			durationSec := hcCPUDurations[m.hcMode]
+			return m, func() tea.Msg {
+				result, err := m.app.RunCPUAcceptancePackResult("", durationSec)
+				return resultMsg{title: result.Title, body: result.Body, err: err, back: screenHealthCheck}
+			}
 		}
 	case "ctrl+c":
 		return m, tea.Quit
@@ -103,7 +110,7 @@ func (m model) confirmCancelTarget() screen {
 	switch m.pendingAction {
 	case actionExportBundle:
 		return screenExportTargets
-	case actionRunAll, actionRunMemorySAT, actionRunStorageSAT:
+	case actionRunAll, actionRunMemorySAT, actionRunStorageSAT, actionRunCPUSAT:
 		return screenHealthCheck
 	default:
 		return screenMain