chore: scaffold Gradle project structure

.gitignore

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+.gradle/
+build/
+*.class

build.gradle.kts

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+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
+plugins {
+    kotlin("jvm") version "2.0.21"
+    application
+}
+
+group = "space.vulp.kestrel"
+version = "0.1.0"
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    testImplementation(kotlin("test"))
+}
+
+kotlin {
+    compilerOptions {
+        jvmTarget.set(JvmTarget.JVM_17)
+    }
+}
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_17
+    targetCompatibility = JavaVersion.VERSION_17
+}
+
+application {
+    mainClass.set("kestrel.cli.MainKt")
+    applicationName = "kestrel"
+}
+
+tasks.named<JavaExec>("run") {
+    standardInput = System.`in`
+}
+
+tasks.test {
+    useJUnitPlatform()
+    testLogging {
+        events("passed", "failed", "skipped")
+    }
+}

settings.gradle.kts

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+rootProject.name = "kestrel"