`update_views` skipped the whole interface when either direction measured
0 bytes/s:
if not i.get('bytes_recv_rate_per_sec') or not i.get('bytes_sent_rate_per_sec'):
continue
The guard is `or`, so one idle direction suppressed the alert for *both*. A
send-only interface saturating its uplink went undecorated because its rx rate
happened to be exactly 0, and a receive-only one — a monitor/SPAN port — the
same way. 0 bytes/s is a real measurement, not a missing one.
The rates now default to 0 instead of skipping, which is what the diskio plugin
already does: it dropped this same guard in #3684 and reads the rate through
`or 0` for the same reason.
The WebUI needs no change — `plugin-network.vue` renders `getDecoration(...)`
straight from the server-supplied view, so it inherits this.
Tests: four cases in `TestNetworkPluginZeroRateAlerts`. Three fail before this
change (saturated tx with idle rx, saturated rx with idle tx, and a fully idle
interface reading DEFAULT instead of OK); the fourth — both directions busy —
passes before and after, which is the path that already worked.
`tests/test_plugin_network.py` 39 passed.
Nguyen Thanh Dat