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/rendering/renderer.hpp

@@ -127,7 +127,7 @@ public:
     void setEquippedWeaponType(uint32_t inventoryType) { equippedWeaponInvType_ = inventoryType; meleeAnimId = 0; }
 
     // Mount rendering
-    void setMounted(uint32_t mountInstId, float heightOffset);
+    void setMounted(uint32_t mountInstId, uint32_t mountDisplayId, float heightOffset);
     void setTaxiFlight(bool onTaxi) { taxiFlight_ = onTaxi; }
     void setMountPitchRoll(float pitch, float roll) { mountPitch_ = pitch; mountRoll_ = roll; }
     void clearMount();