feat(android): release signing + R8-verified signed APK (Phase 28.8)

android/app/build.gradle.kts

@@ -1,3 +1,6 @@
+import java.io.FileInputStream
+import java.util.Properties
+
 plugins {
     alias(libs.plugins.android.application)
     alias(libs.plugins.kotlin.android)
@@ -6,6 +9,12 @@ plugins {
     alias(libs.plugins.ksp)
 }
 
+// Release signing config loaded from keystore.properties (gitignored).
+val keystorePropertiesFile = rootProject.file("keystore.properties")
+val keystoreProperties = Properties().apply {
+    if (keystorePropertiesFile.exists()) load(FileInputStream(keystorePropertiesFile))
+}
+
 android {
     namespace = "com.yarisobd.app"
     compileSdk = 35
@@ -20,6 +29,17 @@ android {
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
     }
 
+    signingConfigs {
+        create("release") {
+            if (keystorePropertiesFile.exists()) {
+                storeFile = rootProject.file(keystoreProperties["storeFile"] as String)
+                storePassword = keystoreProperties["storePassword"] as String
+                keyAlias = keystoreProperties["keyAlias"] as String
+                keyPassword = keystoreProperties["keyPassword"] as String
+            }
+        }
+    }
+
     buildTypes {
         debug {
             applicationIdSuffix = ".debug"
@@ -32,6 +52,7 @@ android {
                 getDefaultProguardFile("proguard-android-optimize.txt"),
                 "proguard-rules.pro"
             )
+            signingConfig = signingConfigs.getByName("release")
         }
     }