feat: propagate OBJECT_FIELD_SCALE_X through creature and GO spawn pipeline

Reads OBJECT_FIELD_SCALE_X (field 4, cross-expansion) from CREATE_OBJECT
update fields and passes it through the full creature and game object spawn
chain: game_handler callbacks → pending spawn structs → async load results
→ createInstance() calls. This gives boss giants, gnomes, children, and
other non-unit-scale NPCs correct visual size, and ensures scaled GOs
(e.g. large treasure chests, oversized plants) render at the server-specified
scale rather than always at 1.0.

- Added OBJECT_FIELD_SCALE_X to UF enum and all expansion update_fields.json
- Added float scale to CreatureSpawnCallback and GameObjectSpawnCallback
- Propagated scale through PendingCreatureSpawn, PreparedCreatureModel,
  PendingGameObjectSpawn, PreparedGameObjectWMO
- Used scale in charRenderer/m2Renderer/wmoRenderer createInstance() calls
- Sanity-clamped raw float to [0.01, 100.0] range before use

Data/expansions/turtle/update_fields.json

@@ -1,5 +1,6 @@
 {
   "OBJECT_FIELD_ENTRY": 3,
+  "OBJECT_FIELD_SCALE_X": 4,
   "UNIT_FIELD_TARGET_LO": 16,
   "UNIT_FIELD_TARGET_HI": 17,
   "UNIT_FIELD_BYTES_0": 36,