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/app/app_test.go

@@ -100,6 +100,7 @@ type fakeSAT struct {
 	runNvidiaFn  func(string) (string, error)
 	runMemoryFn  func(string) (string, error)
 	runStorageFn func(string) (string, error)
+	runCPUFn     func(string, int) (string, error)
 }
 
 func (f fakeSAT) RunNvidiaAcceptancePack(baseDir string) (string, error) {
@@ -122,6 +123,13 @@ func (f fakeSAT) RunStorageAcceptancePack(baseDir string) (string, error) {
 	return f.runStorageFn(baseDir)
 }
 
+func (f fakeSAT) RunCPUAcceptancePack(baseDir string, durationSec int) (string, error) {
+	if f.runCPUFn != nil {
+		return f.runCPUFn(baseDir, durationSec)
+	}
+	return "", nil
+}
+
 func TestNetworkStatusFormatsInterfacesAndRoute(t *testing.T) {
 	t.Parallel()