refactor(audio): 볼륨 0일 때 재생 스킵 및 풀 크기 조정

lib/src/core/audio/audio_service.dart

@@ -216,6 +216,7 @@ class AudioService {
   Future<void> playBgm(String name) async {
     if (_isPaused) return;
     if (!_staticInitialized) await init();
+    if (_bgmVolume == 0) return; // 볼륨 0이면 재생 안함
     if (_currentBgm == name) return;
     if (_staticBgmPlayer == null) return;
 
@@ -376,6 +377,7 @@ class AudioService {
   /// 플레이어 이펙트 SFX 재생
   Future<void> playPlayerSfx(String name) async {
     if (_isPaused) return;
+    if (_sfxVolume == 0) return; // 볼륨 0이면 재생 안함
     if (!_staticInitialized) await init();
     _tryPlayPendingBgm();
     await _playerSfxPool?.play('assets/audio/sfx/$name.mp3');
@@ -384,6 +386,7 @@ class AudioService {
   /// 몬스터 이펙트 SFX 재생
   Future<void> playMonsterSfx(String name) async {
     if (_isPaused) return;
+    if (_sfxVolume == 0) return; // 볼륨 0이면 재생 안함
     if (!_staticInitialized) await init();
     _tryPlayPendingBgm();
     await _monsterSfxPool?.play('assets/audio/sfx/$name.mp3');
@@ -412,7 +415,13 @@ class AudioService {
     _bgmVolume = volume.clamp(0.0, 1.0);
     if (_staticBgmPlayer != null) {
       try {
-        await _staticBgmPlayer!.setVolume(_bgmVolume);
+        // 볼륨 0이면 BGM 정지
+        if (_bgmVolume == 0) {
+          await _staticBgmPlayer!.stop();
+          _currentBgm = null;
+        } else {
+          await _staticBgmPlayer!.setVolume(_bgmVolume);
+        }
       } catch (_) {}
     }
     await _settingsRepository.saveBgmVolume(_bgmVolume);