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.

frontend/src/components/SettingsModal.tsx

@@ -16,7 +16,7 @@ import {
   GetTunerGeniusSettings, SaveTunerGeniusSettings,
   GetAmplifiers, SaveAmplifiers, GetAmpStatuses, AmpOperate,
   GetWinkeyerSettings, SaveWinkeyerSettings, ListSerialPorts,
-  GetAudioSettings, SaveAudioSettings, ListAudioInputDevices, ListAudioOutputDevices, PickAudioFolder, TestPTT,
+  GetAudioSettings, SaveAudioSettings, AudioApplyLevels, ListAudioInputDevices, ListAudioOutputDevices, PickAudioFolder, TestPTT,
   GetClublogCtyInfo, SetClublogCtyEnabled, DownloadClublogCty,
   GetClublogMostWantedInfo, SetClublogMostWantedEnabled, DownloadClublogMostWanted,
   GetSecretStatus, SetPassphrase, RemovePassphrase,
@@ -5115,13 +5115,13 @@ export function SettingsModal({ onClose, onSaved, initialSection, onMainPaneChan
             <Label className="text-sm">{t('aud.fromLevel')}</Label>
             <div className="flex items-center gap-2">
               <input type="range" min={10} max={300} step={5} value={audioCfg.from_gain}
-                onChange={(e) => setAudioField({ from_gain: parseInt(e.target.value, 10) })} className="w-48 accent-primary" />
+                onChange={(e) => { const v = parseInt(e.target.value, 10); setAudioField({ from_gain: v }); AudioApplyLevels(v, audioCfg.mic_gain); }} className="w-48 accent-primary" />
               <span className="font-mono text-xs w-12 text-right">{audioCfg.from_gain}%</span>
             </div>
             <Label className="text-sm">{t('aud.micLevel')}</Label>
             <div className="flex items-center gap-2">
               <input type="range" min={10} max={300} step={5} value={audioCfg.mic_gain}
-                onChange={(e) => setAudioField({ mic_gain: parseInt(e.target.value, 10) })} className="w-48 accent-primary" />
+                onChange={(e) => { const v = parseInt(e.target.value, 10); setAudioField({ mic_gain: v }); AudioApplyLevels(audioCfg.from_gain, v); }} className="w-48 accent-primary" />
               <span className="font-mono text-xs w-12 text-right">{audioCfg.mic_gain}%</span>
             </div>
           </div>