Add authentication

shared/build.gradle.kts

@@ -3,6 +3,7 @@ plugins {
     // which requires the Android Gradle Plugin to already be on the project.
     alias(libs.plugins.androidLibrary)
     id("recipe.kotlin.multiplatform")
+    alias(libs.plugins.kotlinSerialization)
     id("recipe.quality")
 }
 
@@ -15,20 +16,30 @@ kotlin {
 
     sourceSets {
         commonMain.dependencies {
-            // Phase 1: intentionally empty. Domain models + DTOs land Phase 2+.
-            // D-19 / INFRA-06: No Ktor, Compose, SQLDelight, Koin, or Kermit here — EVER.
+            // Phase 2: DTOs land here (MeResponse/User per D-27). kotlinx.serialization
+            // is the only allowed runtime dependency in shared/commonMain — D-19 / INFRA-06
+            // forbids Ktor, Compose, SQLDelight, Koin, Kermit. `api(...)` so consumers
+            // (composeApp, server) inherit the @Serializable runtime without each
+            // re-declaring it.
+            api(libs.kotlinx.serializationJson)
         }
     }
 }
 
 android {
     namespace = "dev.ulfrx.recipe.shared"
-    compileSdk = libs.versions.android.compileSdk.get().toInt()
+    compileSdk =
+        libs.versions.android.compileSdk
+            .get()
+            .toInt()
     compileOptions {
         sourceCompatibility = JavaVersion.VERSION_11
         targetCompatibility = JavaVersion.VERSION_11
     }
     defaultConfig {
-        minSdk = libs.versions.android.minSdk.get().toInt()
+        minSdk =
+            libs.versions.android.minSdk
+                .get()
+                .toInt()
     }
 }