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_test.go

@@ -352,6 +352,45 @@ func (f fakeSAT) RunScenario(_ context.Context, baseDir string, _ platform.Scena
 	return "", nil
 }
 
+// TestWritePCIeGPUStatusesToDBSurfacesLinkSpeedDegradation guards the bug
+// where a PCIe link-speed degradation (e.g. Gen1 instead of Gen4) that the
+// collector already flags as Warning on the hardware snapshot never reached
+// the component-status DB: only SAT diag results wrote pcie:gpu:<vendor>
+// there, and none of the nvidia SAT jobs check PCIe link speed, so the
+// DB-backed "check passed" status stayed OK despite the degraded link.
+func TestWritePCIeGPUStatusesToDBSurfacesLinkSpeedDegradation(t *testing.T) {
+	db, err := OpenComponentStatusDB(filepath.Join(t.TempDir(), "component-status.json"))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	class := "VideoController"
+	vendor := 0x10de // collector.NvidiaVendorID
+	status := "Warning"
+	desc := "PCIe link speed degraded: running at Gen1, capable of Gen4"
+	devices := []schema.HardwarePCIeDevice{
+		{
+			HardwareComponentStatus: schema.HardwareComponentStatus{Status: &status, ErrorDescription: &desc},
+			DeviceClass:             &class,
+			VendorID:                &vendor,
+			BDF:                     strPtr("0000:01:00.0"),
+		},
+	}
+
+	writePCIeGPUStatusesToDB(db, devices)
+
+	rec, ok := db.Get("pcie:gpu:nvidia")
+	if !ok {
+		t.Fatal("expected pcie:gpu:nvidia record to be written")
+	}
+	if rec.Status != "Warning" {
+		t.Fatalf("expected Warning, got %q", rec.Status)
+	}
+	if rec.ErrorSummary != desc {
+		t.Fatalf("expected error summary %q, got %q", desc, rec.ErrorSummary)
+	}
+}
+
 func TestRunNCCLTestsPassesSelectedGPUs(t *testing.T) {
 	t.Parallel()