feat(角色): 更新KukeMC角色资源与逻辑

添加KukeMC角色的新动画资源(pico-a.svg, pico-b.svg, pico-c.svg, pico-d.svg)
调整角色基础属性和技能逻辑：
- 增加百分比生命值计算方法
- 修改攻击冷却时间和治疗机制
- 优化子弹生成逻辑
- 更新角色纹理和动画帧
- 调整碰撞框大小和位置

resources/characters/kukemc/pico-d.svg.import

@@ -0,0 +1,43 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://cvig26vtcyqmd"
+path="res://.godot/imported/pico-d.svg-70b0eb2ee6f86ca392e82f97c8126ba0.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://resources/characters/kukemc/pico-d.svg"
+dest_files=["res://.godot/imported/pico-d.svg-70b0eb2ee6f86ca392e82f97c8126ba0.ctex"]
+
+[params]
+
+compress/mode=0
+compress/high_quality=false
+compress/lossy_quality=0.7
+compress/uastc_level=0
+compress/rdo_quality_loss=0.0
+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/channel_remap/red=0
+process/channel_remap/green=1
+process/channel_remap/blue=2
+process/channel_remap/alpha=3
+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
+svg/scale=1.0
+editor/scale_with_editor_scale=false
+editor/convert_colors_with_editor_theme=false