feat(grafana): lab services, WireGuard, lab-overview and DUT improvements

[ccasanueva7]

Summary

• orchestrator dashboard: new Lab Services section (labgrid-exporter, pdudaemon, ser2net state stats + history timeline)
• orchestrator dashboard: new WireGuard section (wg0 bandwidth, packets, errors, link status)
• lab-overview dashboard (new): consolidated view of all DUTs — scrape up/down, uptime, CPU%, RAM%, firmware table
• DUTs dashboard: network errors & drops panel added to Network section

Test plan

• Open Grafana and verify the three dashboards load without errors
• Lab Services section shows green for labgrid-exporter, pdudaemon, ser2net when services are running
• WireGuard panels show traffic on wg0 when CI is active
• Lab Overview shows correct scrape status per device
• DUTs dashboard shows network errors panel (should be near zero in normal conditions)