fix: the audio level sliders did nothing until Settings were saved

Reported again after the monitor was wired up: 300% still sounded like 10%. The
monitor fix was right but could not show, because the sliders only changed the
settings panel's own state — the value reached the audio engine when the
operator clicked Save.

A level is set by ear, by dragging. It now applies on every move, to the monitor
and to the recorder mix alike; saving still persists it. Both halves were needed
and neither works alone.

app.go

@@ -8901,6 +8901,30 @@ func (a *App) DVKStop() {
 	}
 }
 
+// AudioApplyLevels applies the RX and mic levels IMMEDIATELY, without saving.
+//
+// A level is set by ear, by dragging: the sliders only touched the settings
+// panel state, so the value reached the audio engine when the operator clicked
+// Save — and while they were listening and dragging, 10%% sounded exactly like
+// 300%%. The control was not weak, it was not connected to anything yet.
+//
+// Persisting still happens on Save. This is the live half.
+func (a *App) AudioApplyLevels(fromPct, micPct int) {
+	if a.audioMgr != nil {
+		a.audioMgr.SetMonitorGain(fromPct)
+	}
+	if a.qsoRec != nil {
+		f, m := float64(fromPct)/100, float64(micPct)/100
+		if fromPct <= 0 {
+			f = 1
+		}
+		if micPct <= 0 {
+			m = 1
+		}
+		a.qsoRec.SetGains(f, m)
+	}
+}
+
 // AudioStartMonitor pipes live RX audio from the rig into your speakers so you
 // hear the radio inside OpsLog. Source = the "From radio" capture device (for a
 // USB-connected rig, its "USB Audio CODEC" input); sink = the "Listening"