✨ 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/build.gradle.kts

@@ -0,0 +1,54 @@
+plugins {
+    kotlin("jvm") version "2.1.21"
+    application
+    id("com.github.johnrengelman.shadow") version "8.1.1"
+}
+
+group = "com.soundforce.apisign"
+version = "1.0.0"
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation(kotlin("stdlib"))
+    implementation("org.jetbrains.kotlinx:kotlinx-cli:0.3.6")
+    implementation("io.github.cdimascio:dotenv-kotlin:6.5.1")
+    testImplementation(kotlin("test"))
+}
+
+application {
+    mainClass.set("com.soundforce.apisign.MainKt")
+}
+
+tasks.test {
+    useJUnitPlatform()
+}
+
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(21))
+    }
+}
+
+tasks.withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompile> {
+    kotlinOptions {
+        jvmTarget = "21"
+    }
+}
+
+tasks.jar {
+    manifest {
+        attributes["Main-Class"] = "com.soundforce.apisign.MainKt"
+    }
+    duplicatesStrategy = DuplicatesStrategy.EXCLUDE
+    from(configurations.runtimeClasspath.get().map { if (it.isDirectory) it else zipTree(it) })
+}
+
+tasks.shadowJar {
+    archiveBaseName.set("apisign")
+    archiveClassifier.set("")
+    archiveVersion.set("1.0.0")
+    mergeServiceFiles()
+}