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

Data/expansions/turtle/update_fields.json

@@ -12,6 +12,7 @@
   "UNIT_FIELD_FLAGS": 46,
   "UNIT_FIELD_DISPLAYID": 131,
   "UNIT_FIELD_MOUNTDISPLAYID": 133,
+  "UNIT_FIELD_AURAS": 50,
   "UNIT_NPC_FLAGS": 147,
   "UNIT_DYNAMIC_FLAGS": 143,
   "UNIT_END": 188,