build: 配置 Android Release 签名和构建优化

- 添加 Release 签名配置 (build.gradle.kts)
- 配置 ProGuard 混淆规则 (proguard-rules.pro)
- 优化 Gradle 内存配置 (gradle.properties)
- 更新 .gitignore 排除签名密钥文件

签名密钥存放于 publish/ 目录 (已排除版本控制)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

frontend/mobile-app/.gitignore

@@ -43,3 +43,9 @@ app.*.map.json
 /android/app/debug
 /android/app/profile
 /android/app/release
+
+# Release signing keys (IMPORTANT: never commit these!)
+/publish/
+*.keystore
+*.jks
+key.properties

frontend/mobile-app/android/app/build.gradle.kts

@@ -1,3 +1,6 @@
+import java.util.Properties
+import java.io.FileInputStream
+
 plugins {
     id("com.android.application")
     id("kotlin-android")
@@ -5,6 +8,13 @@ plugins {
     id("dev.flutter.flutter-gradle-plugin")
 }
 
+// Load key.properties
+val keyPropertiesFile = rootProject.file("app/../publish/key.properties")
+val keyProperties = Properties()
+if (keyPropertiesFile.exists()) {
+    keyProperties.load(FileInputStream(keyPropertiesFile))
+}
+
 android {
     namespace = "com.rwadurian.rwa_android_app"
     compileSdk = flutter.compileSdkVersion
@@ -30,11 +40,30 @@ android {
         versionName = flutter.versionName
     }
 
+    signingConfigs {
+        create("release") {
+            if (keyPropertiesFile.exists()) {
+                keyAlias = keyProperties["keyAlias"] as String
+                keyPassword = keyProperties["keyPassword"] as String
+                storeFile = file(keyProperties["storeFile"] as String)
+                storePassword = keyProperties["storePassword"] as String
+            }
+        }
+    }
+
     buildTypes {
         release {
-            // TODO: Add your own signing config for the release build.
-            // Signing with the debug keys for now, so `flutter run --release` works.
-            signingConfig = signingConfigs.getByName("debug")
+            signingConfig = if (keyPropertiesFile.exists()) {
+                signingConfigs.getByName("release")
+            } else {
+                signingConfigs.getByName("debug")
+            }
+            isMinifyEnabled = true
+            isShrinkResources = true
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro"
+            )
         }
     }
 }

frontend/mobile-app/android/app/proguard-rules.pro

@@ -0,0 +1,45 @@
+# Flutter wrapper
+-keep class io.flutter.app.** { *; }
+-keep class io.flutter.plugin.**  { *; }
+-keep class io.flutter.util.**  { *; }
+-keep class io.flutter.view.**  { *; }
+-keep class io.flutter.**  { *; }
+-keep class io.flutter.plugins.**  { *; }
+
+# Google Play Core (suppress warnings for deferred components)
+-dontwarn com.google.android.play.core.splitcompat.SplitCompatApplication
+-dontwarn com.google.android.play.core.splitinstall.SplitInstallException
+-dontwarn com.google.android.play.core.splitinstall.SplitInstallManager
+-dontwarn com.google.android.play.core.splitinstall.SplitInstallManagerFactory
+-dontwarn com.google.android.play.core.splitinstall.SplitInstallRequest$Builder
+-dontwarn com.google.android.play.core.splitinstall.SplitInstallRequest
+-dontwarn com.google.android.play.core.splitinstall.SplitInstallSessionState
+-dontwarn com.google.android.play.core.splitinstall.SplitInstallStateUpdatedListener
+-dontwarn com.google.android.play.core.tasks.OnFailureListener
+-dontwarn com.google.android.play.core.tasks.OnSuccessListener
+-dontwarn com.google.android.play.core.tasks.Task
+
+# Keep Kotlin metadata
+-keep class kotlin.Metadata { *; }
+
+# Keep web3dart classes
+-keep class org.web3j.** { *; }
+-dontwarn org.web3j.**
+
+# Keep crypto classes
+-keep class org.bouncycastle.** { *; }
+-dontwarn org.bouncycastle.**
+
+# Keep Gson classes
+-keepattributes Signature
+-keepattributes *Annotation*
+-keep class com.google.gson.** { *; }
+
+# Keep R8 from stripping interface information
+-keep,allowobfuscation,allowshrinking interface retrofit2.Call
+-keep,allowobfuscation,allowshrinking class retrofit2.Response
+
+# Keep native methods
+-keepclasseswithmembernames class * {
+    native <methods>;
+}

frontend/mobile-app/android/gradle.properties

@@ -1,2 +1,9 @@
-org.gradle.jvmargs=-Xmx1536m -XX:MaxMetaspaceSize=384m -XX:ReservedCodeCacheSize=256m -XX:+HeapDumpOnOutOfMemoryError
+org.gradle.jvmargs=-Xmx2048m -XX:MaxMetaspaceSize=512m -XX:ReservedCodeCacheSize=256m -XX:+HeapDumpOnOutOfMemoryError -XX:+UseParallelGC
 android.useAndroidX=true
+
+# Disable parallel builds to reduce memory usage
+org.gradle.parallel=false
+org.gradle.caching=true
+
+# Disable lint to reduce memory usage during release build
+android.enableR8.fullMode=false