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/cli/root.go

@@ -98,6 +98,11 @@ func runMonitor(cmd *cobra.Command, cfg *config) error {
 
 	mon := monitor.NewMonitor(specs, cfg.LogFile)
 
+	// The non-VPN physical gateway is the last pane: pane B when there are
+	// two, the only pane when there is one. That is where a Starlink dish,
+	// if present upstream, is detected and its status shown.
+	mon.EnableStarlink(specs[len(specs)-1].Name)
+
 	for _, host := range cfg.Hosts {
 		mon.AddReachabilityHost(host)
 	}