Implement mount ambient sounds

Added full mount sound system with:
- Wing flap sounds for flying mounts (gryphon/wyvern) when moving
- Wing idle/hovering sounds when stationary in air
- Breathing/snorting sounds for ground mounts when idle
- Occasional whinny sounds for ground mounts when moving

Sounds are loaded from MPQ files and played via AudioEngine with
randomized pitch/volume variation. Mount sound manager tracks mount
type, movement state, and flying state to play appropriate ambient
sounds at natural intervals.

Updated setMounted() to accept creature display ID and notify the
mount sound manager, which uses display ID ranges to detect mount
type (flying vs ground).

include/audio/mount_sound_manager.hpp

@@ -2,6 +2,8 @@
 
 #include <string>
 #include <cstdint>
+#include <vector>
+#include <chrono>
 
 namespace wowee {
 namespace pipeline { class AssetManager; }
@@ -15,6 +17,11 @@ enum class MountType {
     SWIMMING     // Sea turtle, etc.
 };
 
+struct MountSample {
+    std::string path;
+    std::vector<uint8_t> data;
+};
+
 class MountSoundManager {
 public:
     MountSoundManager();
@@ -40,6 +47,8 @@ private:
     MountType detectMountType(uint32_t creatureDisplayId) const;
     void updateMountSounds();
     void stopAllMountSounds();
+    void loadMountSounds();
+    bool loadSound(const std::string& path, MountSample& sample);
 
     pipeline::AssetManager* assetManager_ = nullptr;
     bool mounted_ = false;
@@ -49,9 +58,17 @@ private:
     uint32_t currentDisplayId_ = 0;
     float volumeScale_ = 1.0f;
 
+    // Mount sound samples (loaded from MPQ)
+    std::vector<MountSample> wingFlapSounds_;
+    std::vector<MountSample> wingIdleSounds_;
+    std::vector<MountSample> horseBreathSounds_;
+    std::vector<MountSample> horseMoveSounds_;
+
     // Sound state tracking
     bool playingMovementSound_ = false;
     bool playingIdleSound_ = false;
+    std::chrono::steady_clock::time_point lastSoundUpdate_;
+    float soundLoopTimer_ = 0.0f;
 };
 
 } // namespace audio