✨ 添加Java和Kotlin实现的API签名工具，包括核心库、命令行工具和使用文档，支持多种签名算法和环境变量配置。

kotlin/.gitattributes

@@ -0,0 +1,12 @@
+#
+# https://help.github.com/articles/dealing-with-line-endings/
+#
+# Linux start script should use lf
+/gradlew        text eol=lf
+
+# These are Windows script files and should use crlf
+*.bat           text eol=crlf
+
+# Binary files should be left untouched
+*.jar           binary
+