feat(物品系统): 新增沙滩球物品及相关功能

refactor(武器卡片): 调整武器类型和颜色映射
style(UI): 更新武器名称标签样式
fix(实体基础): 修正物品掉落逻辑
perf(音频): 优化音频处理模式
docs(物品存储): 更新物品枚举和映射
build(资源): 添加沙滩球SVG资源文件
chore(资源): 更新篮球和棒球SVG资源

resources/items/beachball.svg.import

@@ -0,0 +1,37 @@
+[remap]
+
+importer="texture"
+type="CompressedTexture2D"
+uid="uid://dw0g7cb4skd5s"
+path="res://.godot/imported/beachball.svg-44c9c9a724c60757f2d6e61f16abf098.ctex"
+metadata={
+"vram_texture": false
+}
+
+[deps]
+
+source_file="res://resources/items/beachball.svg"
+dest_files=["res://.godot/imported/beachball.svg-44c9c9a724c60757f2d6e61f16abf098.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
+svg/scale=1.0
+editor/scale_with_editor_scale=false
+editor/convert_colors_with_editor_theme=false