fix(client): correct second D-160 segment count reference (21→18)

Stig's review fix caught the first reference (line 9) but missed the
class docstring at line 27. Both now say 18 segments per D-160.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

client/scripts/rendering/character_visual.gd

@@ -24,7 +24,7 @@ extends Node3D
 ##   get_accessory_node_count()           — number of accessory BoneAttachment3D nodes
 ##   get_skin_tone_texture_name(index)    — skin tone texture filename key for index
 ##
-## D-159 (11 body types), D-160 (21 segments), D-161 (head separate),
+## D-159 (11 body types), D-160 (18 segments), D-161 (head separate),
 ## D-162 (clothing pre-fitted), D-163 (heads via BoneAttachment3D), D-164 (skeleton fork)
 
 const BASE_PATH := "res://assets/characters/"