feat: increase perceived audio loudness — +3dB master boost, configurable SFX volume

Three changes to bring output volume closer to native apps:
- Insert masterBoost GainNode (+3dB) before the compressor/limiter
- Raise default system sound volume from 0.5 to 0.8
- Add configurable Sound Effects Volume slider (0–200%) in Voice settings

packages/web/src/components/modals/settingsPanels/VoicePanel.tsx

@@ -8,9 +8,36 @@ export function VoicePanel() {
   const setEchoCancellation = useVoiceStore((s) => s.setEchoCancellation);
   const setAutoGainControl = useVoiceStore((s) => s.setAutoGainControl);
   const setRnnoiseEnabled = useVoiceStore((s) => s.setRnnoiseEnabled);
+  const soundEffectVolume = useVoiceStore((s) => s.soundEffectVolume);
+  const setSoundEffectVolume = useVoiceStore((s) => s.setSoundEffectVolume);
 
   return (
     <div className="space-y-5">
+      <div>
+        <div className="text-[11px] font-semibold text-txt-tertiary uppercase tracking-wider mb-1.5">
+          Volume
+        </div>
+        <div className="rounded-lg bg-white/[0.03] border border-white/[0.04] p-3.5">
+          <div className="py-1">
+            <div className="flex items-center justify-between mb-2">
+              <div className="text-sm text-txt-primary">Sound Effects Volume</div>
+              <div className="text-xs text-txt-tertiary tabular-nums">{soundEffectVolume}%</div>
+            </div>
+            <input
+              type="range"
+              min={0}
+              max={200}
+              value={soundEffectVolume}
+              onChange={(e) => setSoundEffectVolume(Number(e.target.value))}
+              className="w-full h-1.5 rounded-full appearance-none cursor-pointer bg-surface-base [&::-webkit-slider-thumb]:appearance-none [&::-webkit-slider-thumb]:w-3 [&::-webkit-slider-thumb]:h-3 [&::-webkit-slider-thumb]:rounded-full [&::-webkit-slider-thumb]:bg-white [&::-webkit-slider-thumb]:shadow-md"
+              style={{
+                background: `linear-gradient(to right, rgb(var(--accent-primary)) 0%, rgb(var(--accent-primary)) ${soundEffectVolume / 2}%, rgb(var(--interactive-muted)) ${soundEffectVolume / 2}%, rgb(var(--interactive-muted)) 100%)`,
+              }}
+            />
+          </div>
+        </div>
+      </div>
+
       <div>
         <div className="text-[11px] font-semibold text-txt-tertiary uppercase tracking-wider mb-1.5">
           Voice Processing