feat(arc): 添加虹软人脸识别插件基础功能

- 集成虹软 ArcSoft Face SDK，提供人脸检测、识别、活体检测功能
- 实现 Android 平台原生插件，包含 ArcPlugin 和 FaceEngineManager
- 添加完整的人脸错误码枚举（586个错误码），覆盖 SDK 所有错误情况
- 创建人脸信息数据模型 FaceInfo，封装检测结果和特征数据
- 配置 Android 权限和依赖，包括相机、存储、网络等必要权限
- 添加方法通道实现，连接 Flutter 层与原生层通信
- 配置项目基础文件，包含 .gitignore、分析选项和元数据配置
- 实现单元测试框架，包含 Dart 和 Java 层的基本测试用例
- 添加示例应用配置，验证插件集成和基本功能使用
- 提供详细的开发指导文档 CLAUDE.md，说明架构和 API 使用方法

example/android/app/build.gradle.kts

@@ -0,0 +1,44 @@
+plugins {
+    id("com.android.application")
+    id("kotlin-android")
+    // The Flutter Gradle Plugin must be applied after the Android and Kotlin Gradle plugins.
+    id("dev.flutter.flutter-gradle-plugin")
+}
+
+android {
+    namespace = "com.xiarui.arc_example"
+    compileSdk = flutter.compileSdkVersion
+    ndkVersion = flutter.ndkVersion
+
+    compileOptions {
+        sourceCompatibility = JavaVersion.VERSION_11
+        targetCompatibility = JavaVersion.VERSION_11
+    }
+
+    kotlinOptions {
+        jvmTarget = JavaVersion.VERSION_11.toString()
+    }
+
+    defaultConfig {
+        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
+        applicationId = "com.xiarui.arc_example"
+        // You can update the following values to match your application needs.
+        // For more information, see: https://flutter.dev/to/review-gradle-config.
+        minSdk = flutter.minSdkVersion
+        targetSdk = flutter.targetSdkVersion
+        versionCode = flutter.versionCode
+        versionName = flutter.versionName
+    }
+
+    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")
+        }
+    }
+}
+
+flutter {
+    source = "../.."
+}