fix(collector): surface PCIe link-speed degradation in component-status DB, sample it under load

pcie:gpu:<vendor> in the component-status DB (what the Hardware
Summary/webui "check passed" status reads) was only ever written by SAT
diag results, and none of the nvidia/nvidia-config/nvidia-interconnect/
nvidia-bandwidth SAT jobs check PCIe link speed. So a real Gen1/Gen4
degradation the collector already flagged as Warning in the hardware
snapshot never reached the DB-backed status, and the audit kept
reporting "OK" despite GPUs training at Gen1 with BMC showing x16.

Add writePCIeGPUStatusesToDB, mirroring the existing PSU write-through,
so RunAudit pushes the collector's PCIe status into the DB alongside
SAT results.

Also add export/gpu/pcie-nvidia-link-under-load.txt to the support
bundle: NVIDIA drivers deliberately downclock PCIe at idle to save
power and re-train to full speed under load, so an idle Gen1 reading
alone can't distinguish real hardware/riser degradation from normal
power management. Resample the same sysfs link attributes while
bee-gpu-burn is actively loading the GPUs so both bundles ship
together.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

audit/internal/app/app.go

@@ -227,6 +227,7 @@ func (a *App) RunAudit(runtimeMode runtimeenv.Mode, output string) (string, erro
 	result := collector.Run(runtimeMode)
 	applyLatestSATStatuses(&result.Hardware, DefaultSATBaseDir, a.StatusDB)
 	writePSUStatusesToDB(a.StatusDB, result.Hardware.PowerSupplies)
+	writePCIeGPUStatusesToDB(a.StatusDB, result.Hardware.PCIeDevices)
 	if health, err := ReadRuntimeHealth(DefaultRuntimeJSONPath); err == nil {
 		result.Runtime = &health
 	}
@@ -450,6 +451,58 @@ func writePSUStatusesToDB(db *ComponentStatusDB, psus []schema.HardwarePowerSupp
 	db.Record("psu:all", source, worstStatus, "")
 }
 
+// writePCIeGPUStatusesToDB records GPU PCIe-link statuses (e.g. link speed
+// degraded to Gen1 while capable of Gen4) collected during audit into the
+// component-status DB. Without this, the DB's pcie:gpu:<vendor> key is only
+// ever written by SAT diag results (ApplySATResultToDB), and none of the
+// nvidia/nvidia-config/nvidia-interconnect/nvidia-bandwidth SAT jobs check
+// PCIe link speed — so a real Gen1/Gen4 degradation the collector already
+// flagged as Warning in the hardware snapshot never surfaces in the DB-backed
+// "check passed" status the Hardware Summary/webui reads.
+func writePCIeGPUStatusesToDB(db *ComponentStatusDB, devices []schema.HardwarePCIeDevice) {
+	if db == nil || len(devices) == 0 {
+		return
+	}
+	const source = "audit:pcie"
+	worst := map[string]string{}
+	detail := map[string]string{}
+	for _, dev := range devices {
+		if dev.Status == nil {
+			continue
+		}
+		st := *dev.Status
+		for _, vendor := range []string{"nvidia", "amd"} {
+			if !matchesGPUVendor(dev, vendor) {
+				continue
+			}
+			if _, seen := worst[vendor]; !seen {
+				worst[vendor] = "OK"
+			}
+			switch st {
+			case "Critical":
+				worst[vendor] = "Critical"
+				if dev.ErrorDescription != nil {
+					detail[vendor] = *dev.ErrorDescription
+				}
+			case "Warning":
+				if worst[vendor] != "Critical" {
+					worst[vendor] = "Warning"
+					if dev.ErrorDescription != nil {
+						detail[vendor] = *dev.ErrorDescription
+					}
+				}
+			}
+		}
+	}
+	for _, vendor := range []string{"nvidia", "amd"} {
+		status, present := worst[vendor]
+		if !present {
+			continue
+		}
+		db.Record("pcie:gpu:"+vendor, source, status, detail[vendor])
+	}
+}
+
 func ReadRuntimeHealth(path string) (schema.RuntimeHealth, error) {
 	raw, err := os.ReadFile(path)
 	if err != nil {