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.

contracts/ping-api/build.gradle.kts

@@ -0,0 +1,39 @@
+plugins {
+    alias(libs.plugins.kotlinMultiplatform)
+    alias(libs.plugins.kotlinSerialization)
+}
+
+group = "at.mocode"
+version = "1.0.0"
+
+kotlin {
+    // Toolchain is now handled centrally in the root build.gradle.kts
+
+    // JVM target for backend usage
+    jvm()
+
+    // JS target for frontend usage (Compose/Browser)
+    js {
+        browser()
+        // no need for binaries.executable() in a library
+    }
+
+    // Wasm enabled by default
+    @OptIn(org.jetbrains.kotlin.gradle.ExperimentalWasmDsl::class)
+    wasmJs {
+        browser()
+    }
+
+    sourceSets {
+        commonMain {
+            dependencies {
+                implementation(libs.kotlinx.serialization.json)
+            }
+        }
+        commonTest {
+            dependencies {
+                implementation(libs.kotlin.test)
+            }
+        }
+    }
+}

contracts/ping-api/src/commonMain/kotlin/at/mocode/ping/api/PingApi.kt

@@ -0,0 +1,7 @@
+package at.mocode.ping.api
+
+interface PingApi {
+    suspend fun simplePing(): PingResponse
+    suspend fun enhancedPing(simulate: Boolean = false): EnhancedPingResponse
+    suspend fun healthCheck(): HealthResponse
+}

contracts/ping-api/src/commonMain/kotlin/at/mocode/ping/api/PingData.kt

@@ -0,0 +1,23 @@
+package at.mocode.ping.api
+
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class PingResponse(val status: String, val timestamp: String, val service: String)
+
+@Serializable
+data class EnhancedPingResponse(
+    val status: String,
+    val timestamp: String,
+    val service: String,
+    val circuitBreakerState: String,
+    val responseTime: Long
+)
+
+@Serializable
+data class HealthResponse(
+    val status: String,
+    val timestamp: String,
+    val service: String,
+    val healthy: Boolean
+)