Warn on PCIe link speed degradation and collect lspci -vvv in techdump

- collector/pcie: add applyPCIeLinkSpeedWarning that sets status=Warning
  and ErrorDescription when current link speed is below maximum negotiated
  speed (e.g. Gen1 running on a Gen5 slot)
- collector/pcie: add pcieLinkSpeedRank helper for Gen string comparison
- collector/pcie_filter_test: cover degraded and healthy link speed cases
- platform/techdump: collect lspci -vvv → lspci-vvv.txt for LnkCap/LnkSta

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

audit/internal/platform/techdump.go

@@ -20,6 +20,7 @@ var techDumpFixedCommands = []struct {
 	{Name: "dmidecode", Args: []string{"-t", "4"}, File: "dmidecode-type4.txt"},
 	{Name: "dmidecode", Args: []string{"-t", "17"}, File: "dmidecode-type17.txt"},
 	{Name: "lspci", Args: []string{"-vmm", "-D"}, File: "lspci-vmm.txt"},
+	{Name: "lspci", Args: []string{"-vvv"}, File: "lspci-vvv.txt"},
 	{Name: "lsblk", Args: []string{"-J", "-d", "-o", "NAME,TYPE,SIZE,SERIAL,MODEL,TRAN,HCTL"}, File: "lsblk.json"},
 	{Name: "sensors", Args: []string{"-j"}, File: "sensors.json"},
 	{Name: "ipmitool", Args: []string{"fru", "print"}, File: "ipmitool-fru.txt"},