Collect IPMI sensors, SEL and dmesg errors into audit JSON and support bundle

- audit JSON: IPMI sensor readings (ipmitool sensor) merged into hardware.sensors alongside lm-sensors data
- audit JSON: IPMI SEL entries (ipmitool sel list) in hardware.event_logs with source "ipmi-sel"
- audit JSON: dmesg error/warning lines in hardware.event_logs with source "dmesg" (filtered by error/warn/AER/Xid/NVRM/ECC/panic patterns)
- support bundle: added ipmitool-sensor.txt, ipmitool-sel.txt, ipmitool-sel-time.txt to techdump
- saa_dmi.go: fix dmiItemRE to accept SHN with parentheses (e.g. PS(4)LC for PSU fields)

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

audit/internal/platform/techdump.go

@@ -25,6 +25,9 @@ var techDumpFixedCommands = []struct {
 	{Name: "sensors", Args: []string{"-j"}, File: "sensors.json"},
 	{Name: "ipmitool", Args: []string{"fru", "print"}, File: "ipmitool-fru.txt"},
 	{Name: "ipmitool", Args: []string{"sdr"}, File: "ipmitool-sdr.txt"},
+	{Name: "ipmitool", Args: []string{"sensor"}, File: "ipmitool-sensor.txt"},
+	{Name: "ipmitool", Args: []string{"sel", "list"}, File: "ipmitool-sel.txt"},
+	{Name: "ipmitool", Args: []string{"sel", "time", "get"}, File: "ipmitool-sel-time.txt"},
 	{Name: "nvme", Args: []string{"list", "-o", "json"}, File: "nvme-list.json"},
 }