refactor(ping-service): remove CORS configuration from code, restructure modules, and update Gradle dependencies

Migrated CORS settings from code to `application.yaml` for better separation of concerns. Integrated `ping-api` into the new `contracts` module for improved modularity. Updated Gradle scripts and dependencies accordingly to reflect the new project structure.

build.gradle.kts

@@ -10,7 +10,7 @@ import java.util.zip.GZIPOutputStream
 
 plugins {
   // Version management plugin for dependency updates
-  id("com.github.ben-manes.versions") version "0.51.0"
+  alias(libs.plugins.benManesVersions)
 
   // Kotlin plugins declared here with 'apply false' to centralize version management
   // This prevents "plugin loaded multiple times" errors in Gradle 9.2.1+
@@ -29,8 +29,8 @@ plugins {
   alias(libs.plugins.dokka)
 
   // Static analysis (enabled at root and inherited by subprojects)
-  id("io.gitlab.arturbosch.detekt") version "1.23.6"
-  id("org.jlleitschuh.gradle.ktlint") version "12.1.1"
+  alias(libs.plugins.detekt)
+  alias(libs.plugins.ktlint)
 }
 
 // ##################################################################
@@ -80,14 +80,6 @@ subprojects {
     // The agent configuration was causing Task.project access at execution time
   }
 
-  // Erzwinge eine stabile Version von kotlinx-serialization-json für alle Konfigurationen,
-  // um Auflösungsfehler (z.B. 1.10.2, nicht verfügbar auf Maven Central) zu vermeiden
-  configurations.configureEach {
-    resolutionStrategy {
-      force("org.jetbrains.kotlinx:kotlinx-serialization-json:1.7.3")
-    }
-  }
-
   // Dedicated performance test task per JVM subproject
   plugins.withId("java") {
     val javaExt = extensions.getByType<JavaPluginExtension>()