redfish: MSI support, fix zero dates, BMC MAC, Assembly FRU, crawler cleanup

- Add MSI CG480-S5063 (H100 SXM5) support:
  - collectGPUsFromProcessors: find GPUs via Processors/ProcessorType=GPU,
    resolve serials from Chassis/<GpuId>
  - looksLikeGPU: skip Description="Display Device" PCIe sidecars
  - isVirtualStorageDrive: filter AMI virtual USB drives (0-byte)
  - enrichNICMACsFromNetworkDeviceFunctions: pull MACs for MSI NICs
  - parseCPUs: filter by ProcessorType, parse Socket, L1/L2/L3 from ProcessorMemory
  - parseMemory: Location.PartLocation.ServiceLabel slot fallback
  - shouldCrawlPath: block /SubProcessors subtrees
- Fix status_checked_at/status_changed_at serializing as 0001-01-01:
  change all StatusCheckedAt/StatusChangedAt fields to *time.Time
- Redfish crawler cleanup:
  - Block non-inventory branches: AccountService, CertificateService,
    EventService, Registries, SessionService, TaskService, manager config paths,
    OperatingConfigs, BootOptions, HostPostCode, Bios/Settings, OEM KVM paths
  - Add Assembly to critical endpoints (FRU data)
  - Remove BootOptions from priority seeds
- collectBMCMAC: read BMC MAC from Managers/*/EthernetInterfaces
- collectAssemblyFRU: extract FRU serial/part from Chassis/*/Assembly
- Firmware: remove NetworkProtocol noise, fix SecureBoot field,
  filter BMCImageN redundant backup slots

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

internal/parser/vendors/nvidia/component_status_time.go

@@ -230,7 +230,7 @@ func ApplyGPUAndNVSwitchCheckTimes(result *models.AnalysisResult, times componen
 		if ts.IsZero() {
 			continue
 		}
-		gpu.StatusCheckedAt = ts
+		gpu.StatusCheckedAt = &ts
 		status := strings.TrimSpace(gpu.Status)
 		if status == "" {
 			status = "Unknown"
@@ -261,7 +261,7 @@ func ApplyGPUAndNVSwitchCheckTimes(result *models.AnalysisResult, times componen
 			continue
 		}
 
-		dev.StatusCheckedAt = ts
+		dev.StatusCheckedAt = &ts
 		status := strings.TrimSpace(dev.Status)
 		if status == "" {
 			status = "Unknown"