Refine node mesh scaling logic

We now do scale static meshes, as the bug that caused meshes not to be scaled was limited to skeletally animated meshes,
hence we ought not to reproduce it for skinned meshes that do not take advantage of skeletal animations (e.g. current MTG doors).

However, gltf models (e.g. Wuzzy's eyeballs) up until recently were always affected due to technical reasons
(using skeletal animation for rigid animation).

Thus, to preserve behavior, we:

1. Do not apply 10x scale to glTF models.
2. Apply 10x scale to obj models.
3. Apply 10x scale to static x or b3d models, but not to animated ones.

doc/lua_api.md

@@ -10172,9 +10172,12 @@ Used by `core.register_node`.
     mesh = "",
     -- File name of mesh when using "mesh" drawtype
     -- The center of the node is the model origin.
-    -- For legacy reasons, models in OBJ format use a scale of 1 node = 1 unit;
-    -- all other model file formats use a scale of 1 node = 10 units,
-    -- consistent with the scale used for entities.
+    -- For legacy reasons, this uses a different scale depending on the mesh:
+    -- 1. For glTF models: 10 units = 1 node (consistent with the scale for entities).
+    -- 2. For obj models: 1 unit = 1 node.
+    -- 3. For b3d and x models: 1 unit = 1 node if static, otherwise 10 units = 1 node.
+    -- Using static glTF or obj models is recommended.
+    -- You can use the `visual_scale` multiplier to achieve the expected scale.
 
     selection_box = {
         -- see [Node boxes] for possibilities