Add mute button and original soundtrack toggle

- Mute button: small [M] button alongside minimap zoom controls, turns red when active; directly sets AudioEngine master volume to 0, restores on unmute; persists in settings.cfg
- Original Soundtrack: checkbox in Settings > Audio that controls whether custom original music tracks (file: prefix) are included in zone music rotation; when disabled, only WoW MPQ tracks play; persists in settings.cfg
- ZoneManager.getRandomMusic() now filters file: paths when OST is disabled, falling back to full list if zone has no non-file tracks

include/game/zone_manager.hpp

@@ -23,11 +23,16 @@ public:
     std::string getRandomMusic(uint32_t zoneId);
     std::vector<std::string> getAllMusicPaths() const;
 
+    // When false, file: (original soundtrack) tracks are excluded from the pool
+    void setUseOriginalSoundtrack(bool use) { useOriginalSoundtrack_ = use; }
+    bool getUseOriginalSoundtrack() const { return useOriginalSoundtrack_; }
+
 private:
     // tile key = tileX * 100 + tileY
     std::unordered_map<int, uint32_t> tileToZone;
     std::unordered_map<uint32_t, ZoneInfo> zones;
     std::string lastPlayedMusic_;
+    bool useOriginalSoundtrack_ = true;
 };
 
 } // namespace game

include/rendering/renderer.hpp

@@ -155,6 +155,7 @@ public:
     double getLastWMORenderMs() const { return lastWMORenderMs; }
     double getLastM2RenderMs() const { return lastM2RenderMs; }
     audio::MusicManager* getMusicManager() { return musicManager.get(); }
+    game::ZoneManager* getZoneManager() { return zoneManager.get(); }
     audio::FootstepManager* getFootstepManager() { return footstepManager.get(); }
     audio::ActivitySoundManager* getActivitySoundManager() { return activitySoundManager.get(); }
     audio::MountSoundManager* getMountSoundManager() { return mountSoundManager.get(); }

include/ui/game_screen.hpp

@@ -97,6 +97,7 @@ private:
     bool pendingMinimapRotate = false;
     bool pendingMinimapSquare = false;
     bool pendingSeparateBags = true;
+    bool pendingUseOriginalSoundtrack = true;
 
     // UI element transparency (0.0 = fully transparent, 1.0 = fully opaque)
     float uiOpacity_ = 0.65f;
@@ -104,6 +105,10 @@ private:
     bool minimapSquare_ = false;
     bool minimapSettingsApplied_ = false;
 
+    // Mute state: mute bypasses master volume without touching slider values
+    bool soundMuted_ = false;
+    float preMuteVolume_ = 1.0f;  // AudioEngine master volume before muting
+
     /**
      * Render player info window
      */