Fix build.gradle.kts: Remove duplicate tasks and JVM-specific code

- Remove duplicate tasks block that was causing compilation errors
- Remove JVM-specific tasks (JavaCompile, KotlinCompile with JVM target)
- Remove ktor fatJar configuration (not applicable to native)
- Keep only native-relevant configuration
- Build configuration now parses correctly

Note: Full compilation test blocked by network restrictions in this environment
preventing Kotlin/Native toolchain download, but configuration is now valid.

Co-authored-by: alexandru <[email protected]>

Author: Copilot

build.gradle.kts

@@ -90,46 +90,3 @@ tasks {
         reportfileName = "report"
     }
 }
-
-// kotlin {
-//     jvmToolchain(22)
-// }
-
-tasks {
-    withType<JavaCompile>().configureEach {
-        options.release.set(21)
-    }
-
-    withType<org.jetbrains.kotlin.gradle.tasks.KotlinCompile>().configureEach {
-        compilerOptions {
-            jvmTarget.set(org.jetbrains.kotlin.gradle.dsl.JvmTarget.JVM_21)
-            javaParameters.set(true)
-        }
-    }
-
-    named<DependencyUpdatesTask>("dependencyUpdates").configure {
-        fun isNonStable(version: String): Boolean {
-            val stableKeyword = listOf("RELEASE", "FINAL", "GA").any { version.uppercase().contains(it) }
-            val regex = "^[0-9,.v-]+(-r)?$".toRegex()
-            val isStable = stableKeyword || regex.matches(version)
-            return isStable.not()
-        }
-
-        rejectVersionIf {
-            isNonStable(candidate.version) && !isNonStable(currentVersion)
-        }
-        checkForGradleUpdate = true
-        outputFormatter = "html"
-        outputDir = "build/dependencyUpdates"
-        reportfileName = "report"
-    }
-
-    test {
-    }
-}
-
-ktor {
-    fatJar {
-        archiveFileName.set("github-webhook-listener-fat.jar")
-    }
-}