fix(exporter): key PCIe canonical dedup by BDF before serial

canonicalKey used serial_number as the primary merge key for pcie-class
devices (PCIe/GPU/Network), falling back to BDF only when serial was empty.
Multi-port NICs commonly report one serial for the whole physical card
across all of its ports/BDFs (e.g. a dual-port ConnectX-5: same serial,
distinct BDFs 0000:65:00.0/.1, distinct MACs). Keying on serial first
collapsed every port sharing that serial into a single canonical device,
silently dropping all but one port from the export.

BDF now takes priority for pcie-class devices, since it uniquely identifies
one physical PCI function; other device kinds (storage, memory, PSU, etc.)
keep the existing serial-first behavior, which is correct there since a
serial genuinely maps 1:1 to a physical unit for those.

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

internal/exporter/reanimator_converter.go

@@ -718,10 +718,19 @@ func mergeDetailMaps(primary, secondary map[string]any) map[string]any {
 
 func canonicalKey(item models.HardwareDevice) string {
 	kind := canonicalMergeKind(item.Kind)
+	bdf := strings.ToLower(strings.TrimSpace(item.BDF))
+	if kind == "pcie-class" && bdf != "" {
+		// BDF identifies one physical PCI function; prefer it over serial for
+		// pcie-class devices. Multi-port NICs commonly report the same serial
+		// (the physical card's serial) across several BDFs/ports — keying on
+		// serial first would collapse distinct ports into a single record and
+		// silently drop the others.
+		return kind + "|bdf:" + bdf
+	}
 	if sn := normalizedSerial(item.SerialNumber); sn != "" {
 		return kind + "|sn:" + strings.ToLower(sn)
 	}
-	if bdf := strings.ToLower(strings.TrimSpace(item.BDF)); bdf != "" {
+	if bdf != "" {
 		return kind + "|bdf:" + bdf
 	}
 	return ""