fix: apply square curve to volume slider so low positions are genuinely quiet

src/player.js

@@ -637,7 +637,9 @@ function _initBarScrub(bar, fill, onMove) {
 }
 
 export function setVolume(v) {
-  const vol = v / 100;
+  // Square curve: slider 50 → actual 0.25, slider 30 → actual 0.09
+  // Matches how ears perceive loudness (logarithmic) so low values feel genuinely quiet.
+  const vol = Math.pow(v / 100, 2);
   S.audio.volume = vol;
   S.previewAudio.volume = vol;
   const absAudio = document.getElementById('abs-audio');