新增 .gitattributes：统一 LF 行尾，Unity YAML 走专用合并

- Unity 的 YAML 资源（.unity/.prefab/.asset/.meta/.mat/.controller/.anim）统一按 LF 处理，
  避免 macOS 与 Windows 之间因行尾差异出现假改动
- 代码与着色器（.cs/.shader/.hlsl/.cginc/.compute）以及 .uxml/.uss/.json 固定 LF
- 图片、模型、音频、DLL、安装包等标记为 binary，禁止行尾转换与文本 diff
- 场景、预制体等 YAML 文件冲突改用 UnityYAMLMerge；本机需配置 merge.unityyamlmerge 驱动，
  未配置时自动回退为普通合并

库内文件当前已全部为 LF，无需再做 renormalize。

.gitattributes

@@ -0,0 +1,76 @@
+# ============================================================
+# Unity 项目 .gitattributes
+# 行尾统一为 LF，二进制资源禁止转换，Unity YAML 走专用合并
+# ============================================================
+
+# 默认按文本处理，自动识别
+* text=auto
+
+# --- Unity YAML 资源 ---
+*.unity             text eol=lf
+*.prefab            text eol=lf
+*.asset             text eol=lf
+*.meta              text eol=lf
+*.mat               text eol=lf
+*.controller        text eol=lf
+*.anim              text eol=lf
+*.playable          text eol=lf
+*.mask              text eol=lf
+*.physicMaterial    text eol=lf
+*.physicsMaterial2D text eol=lf
+*.asmdef            text eol=lf
+*.asmref            text eol=lf
+*.json              text eol=lf
+
+# --- 代码 / 着色器 / UI ---
+*.cs                text eol=lf
+*.shader            text eol=lf
+*.hlsl              text eol=lf
+*.cginc             text eol=lf
+*.compute           text eol=lf
+*.uxml              text eol=lf
+*.uss               text eol=lf
+
+# --- 二进制资源 ---
+*.png binary
+*.jpg binary
+*.jpeg binary
+*.gif binary
+*.psd binary
+*.tga binary
+*.tif binary
+*.exr binary
+*.hdr binary
+*.bmp binary
+*.fbx binary
+*.obj binary
+*.blend binary
+*.3ds binary
+*.dae binary
+*.wav binary
+*.mp3 binary
+*.ogg binary
+*.aiff binary
+*.mp4 binary
+*.mov binary
+*.webm binary
+*.dll binary
+*.so binary
+*.dylib binary
+*.a binary
+*.bundle binary
+*.unitypackage binary
+*.apk binary
+*.aab binary
+*.app binary
+*.keystore binary
+*.jks binary
+*.p12 binary
+
+# --- Unity YAML 冲突走 UnityYAMLMerge ---
+*.unity      merge=unityyamlmerge
+*.prefab     merge=unityyamlmerge
+*.asset      merge=unityyamlmerge
+*.meta       merge=unityyamlmerge
+*.controller merge=unityyamlmerge
+*.anim       merge=unityyamlmerge