Fix mount sounds, grey WMO meshes, taxi landing, tree animations, and classic dismount

- Per-family mount sounds (kodo, tallstrider, mechanostrider, etc.) detected from M2 model path
- Skip WMO groups with SHOW_SKYBOX flag or all-untextured batches (grey mesh in Orgrimmar)
- Freeze physics during taxi landing until terrain loads to prevent falling through void
- Disable bone animations on tropical vegetation (palm, bamboo, banana, etc.) to fix wiggling
- Snap player to final taxi waypoint on flight completion
- Extract mount aura spell ID from classic UNIT_FIELD_AURAS for CMSG_CANCEL_AURA dismount
- Increase /unstuck forward nudge to 5 units

include/rendering/wmo_renderer.hpp

@@ -309,6 +309,7 @@ private:
         glm::vec3 boundingBoxMax;
 
         uint32_t groupFlags = 0;
+        bool allUntextured = false;  // True if ALL batches use fallback white texture (collision/placeholder group)
 
         // Material batches (start index, count, material ID)
         struct Batch {