feat(角色): 添加角色生成时的行走动画

在Chick角色和EntityBase基类中添加spawn方法，用于在角色生成时播放行走动画

scripts/Contents/Characters/Chick.gd

@@ -11,6 +11,8 @@ func register():
 	attackCooldownMap[0] = 2000
 	attackCooldownMap[1] = 6000
 	attackCooldownMap[2] = 100
+func spawn():
+	texture.play("walk")
 
 func ai():
 	move(currentFocusedBoss.position - position)