fix(audio): the network monitor needs no From-radio device

AudioStartMonitor refused before reaching the network branch when From-radio
was empty — which is the NORMAL network setup, so the new speakers checkbox
un-ticked itself the instant it was ticked. The capture-device requirement now
applies only to the USB path that actually captures.

app.go

@@ -10681,9 +10681,6 @@ func (a *App) AudioStartMonitor() error {
 		return fmt.Errorf("audio not initialized")
 	}
 	cfg, _ := a.GetAudioSettings()
-	if strings.TrimSpace(cfg.FromRadio) == "" {
-		return fmt.Errorf(`no "From radio" capture device set — pick the rig's USB Audio CODEC in Settings → Audio`)
-	}
 	// When the rig's audio arrives over the NETWORK (Icom 50003), the monitor
 	// must be render-only: this button used to start a USB capture from the
 	// "From radio" device as well, and that second producer — often another
@@ -10695,6 +10692,13 @@ func (a *App) AudioStartMonitor() error {
 		applog.Printf("audio: RX monitor start (network sink only → listen=%q)", cfg.ListeningDevice)
 		return a.audioMgr.StartMonitorSink(cfg.ListeningDevice)
 	}
+	// Only the USB path needs a capture device — checked AFTER the network
+	// branch, which needs none: with From-radio empty (the normal network
+	// setup) this refusal was un-ticking the speakers checkbox the instant it
+	// was ticked.
+	if strings.TrimSpace(cfg.FromRadio) == "" {
+		return fmt.Errorf(`no "From radio" capture device set — pick the rig's USB Audio CODEC in Settings → Audio`)
+	}
 	applog.Printf("audio: RX monitor start (from=%q → listen=%q)", cfg.FromRadio, cfg.ListeningDevice)
 	a.audioMgr.SetMonitorGain(cfg.FromGain)
 	return a.audioMgr.StartMonitor(cfg.FromRadio, cfg.ListeningDevice)