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/collector/pcie.go

@@ -2,6 +2,7 @@ package collector
 
 import (
 	"bee/audit/internal/schema"
+	"fmt"
 	"log/slog"
 	"os/exec"
 	"strconv"
@@ -172,6 +173,9 @@ func parseLspciDevice(fields map[string]string) schema.HardwarePCIeDevice {
 
 	// SVendor/SDevice available but not in schema — skip
 
+	// Warn if PCIe link is running below its maximum negotiated speed.
+	applyPCIeLinkSpeedWarning(&dev)
+
 	return dev
 }
 
@@ -241,6 +245,41 @@ func readPCIStringAttribute(bdf, attribute string) (string, bool) {
 	return value, true
 }
 
+// applyPCIeLinkSpeedWarning sets the device status to Warning if the current PCIe link
+// speed is below the maximum negotiated speed supported by both ends.
+func applyPCIeLinkSpeedWarning(dev *schema.HardwarePCIeDevice) {
+	if dev.LinkSpeed == nil || dev.MaxLinkSpeed == nil {
+		return
+	}
+	if pcieLinkSpeedRank(*dev.LinkSpeed) < pcieLinkSpeedRank(*dev.MaxLinkSpeed) {
+		warn := statusWarning
+		dev.Status = &warn
+		desc := fmt.Sprintf("PCIe link speed degraded: running at %s, capable of %s", *dev.LinkSpeed, *dev.MaxLinkSpeed)
+		dev.ErrorDescription = &desc
+	}
+}
+
+// pcieLinkSpeedRank returns a numeric rank for a normalized Gen string (e.g. "Gen4" → 4).
+// Returns 0 for unrecognised values so comparisons fail safe.
+func pcieLinkSpeedRank(gen string) int {
+	switch gen {
+	case "Gen1":
+		return 1
+	case "Gen2":
+		return 2
+	case "Gen3":
+		return 3
+	case "Gen4":
+		return 4
+	case "Gen5":
+		return 5
+	case "Gen6":
+		return 6
+	default:
+		return 0
+	}
+}
+
 func normalizePCILinkSpeed(raw string) string {
 	raw = strings.TrimSpace(strings.ToLower(raw))
 	switch {