Add Starlink status lines for the physical gateway pane (closes #3)

When the non-VPN physical gateway is a Starlink dish, two lines are shown
under that pane: state, uptime, obstruction and alert count; then pop-ping
latency and drop rate with downlink/uplink throughput. They turn red when
the dish is not connected or an alert is active.

Detection is a TCP connect to the dish's fixed endpoint 192.168.100.1:9200,
bound to the physical interface the same way the latency probes bind. Until
a dish answers nothing is drawn and no status is fetched, so an absent dish
adds no noise. Status comes from the dish's local get_status gRPC call.

Detection and the fetch sit behind a small Client interface; the loop and
the pure Render function are tested with a fake, no dish and no network.

Model: opus-4-8

internal/monitor/ui.go

@@ -107,6 +107,11 @@ func (m *Monitor) DrawInterface(scr tcell.Screen, y, w int, st *InterfaceStatus)
 	y = m.drawTCPTable(scr, y, st, tcpHosts)
 	y = drawICMPStats(scr, y, st)
 
+	// The Starlink lines belong to the physical (non-VPN gateway) pane only.
+	if st == m.slPane {
+		y = m.drawStarlink(scr, y)
+	}
+
 	return y
 }