Port Link Integrity (OpenConfig transceiver v1.0.0)

Current OpenConfig transceiver v1.0.0 per-channel link-integrity state for one port: cumulative rx/tx LOS, rx/tx LOL and tx-fault counters (summed over lanes), worst-lane media/host SNR, and the counter increase over the last 24 h and 1 h (reset-safe sum of positive steps, same definition as the risk engine's LOS precursor rule). Computed by one bounded ClickHouse aggregate (24 h, single port) — poll this instead of downloading the 24 h history. available is false when the deployment's schema lacks the columns; reported is false when the device does not expose these leaves (every field is then null — a device that reports nothing is not a device with zero events).