feat(角色): 添加KukeChild角色并增强KukeMC能力

新增KukeChild角色及相关资源文件，包括贴图、场景和脚本
调整KukeMC属性，增加新攻击类型可召唤KukeChild
修改EntityBase基础逻辑，添加spawnTime属性和timeLived方法
移除Rooster.gd中未使用的heal方法

resources/characters/kukechild/KukeChild.png.import

@@ -0,0 +1,34 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://lorraj4pe2lt"
+path="res://.godot/imported/KukeChild.png-4ca0607e1c4594e36fa458519a8a0756.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://resources/characters/kukechild/KukeChild.png"
+dest_files=["res://.godot/imported/KukeChild.png-4ca0607e1c4594e36fa458519a8a0756.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/hdr_compression=1
+compress/normal_map=0
+compress/channel_pack=0
+mipmaps/generate=false
+mipmaps/limit=-1
+roughness/mode=0
+roughness/src_normal=""
+process/fix_alpha_border=true
+process/premult_alpha=false
+process/normal_map_invert_y=false
+process/hdr_as_srgb=false
+process/hdr_clamp_exposure=false
+process/size_limit=0
+detect_3d/compress_to=1