model: add an Android target

Without this Android Studio refuses to import this module

model/build.gradle.kts

@@ -1,11 +1,23 @@
 plugins {
   kotlin("multiplatform")
   kotlin("plugin.serialization")
+  id("com.android.library")
 }
 
 kotlin {
+  android()
   jvm { compilations.all { kotlinOptions.jvmTarget = "11" } }
   sourceSets["commonMain"].apply {
     dependencies { implementation(libs.kotlinx.serialization.core) }
   }
 }
+
+android {
+  compileSdk = 31
+  sourceSets["main"].manifest.srcFile("src/androidMain/AndroidManifest.xml")
+  defaultConfig {
+    minSdk = 23
+    targetSdk = 31
+    consumerProguardFiles("consumer-rules.pro")
+  }
+}