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/platform/sat.go

@@ -74,6 +74,18 @@ func (s *System) RunMemoryAcceptancePack(baseDir string) (string, error) {
 	})
 }
 
+func (s *System) RunCPUAcceptancePack(baseDir string, durationSec int) (string, error) {
+	if durationSec <= 0 {
+		durationSec = 60
+	}
+	return runAcceptancePack(baseDir, "cpu", []satJob{
+		{name: "01-lscpu.log", cmd: []string{"lscpu"}},
+		{name: "02-sensors-before.log", cmd: []string{"sensors"}},
+		{name: "03-stress-ng.log", cmd: []string{"stress-ng", "--cpu", "0", "--cpu-method", "all", "--timeout", fmt.Sprintf("%d", durationSec)}},
+		{name: "04-sensors-after.log", cmd: []string{"sensors"}},
+	})
+}
+
 func (s *System) RunStorageAcceptancePack(baseDir string) (string, error) {
 	if baseDir == "" {
 		baseDir = "/var/log/bee-sat"