feat(core): 设备号改用系统标识，重装不再变成新游客

- Android 读 SSAID、iOS 读 IDFV，均免权限，由原生通道提供，不引插件
- 取不到时回退本地 UUIDv4，替代原来 32 位随机 + 时间戳的拼接

android/app/src/main/kotlin/com/stormg/lumadrama/MainActivity.kt

@@ -12,6 +12,7 @@ import android.os.Build
 import android.os.Bundle
 import android.os.Handler
 import android.os.Looper
+import android.provider.Settings
 import android.util.Rational
 import android.content.pm.PackageManager
 import android.view.WindowManager
@@ -65,6 +66,20 @@ class MainActivity : FlutterActivity() {
                 result.success(false)
             }
         }
+        // 设备标识：SSAID 免权限，卸载重装不变，避免客户端自己生成的 id 每次重装都变
+        MethodChannel(flutterEngine.dartExecutor.binaryMessenger, "com.stormg.lumadrama/device")
+            .setMethodCallHandler { call, result ->
+                if (call.method != "ssaid") {
+                    result.notImplemented()
+                    return@setMethodCallHandler
+                }
+                val value = try {
+                    Settings.Secure.getString(contentResolver, Settings.Secure.ANDROID_ID)
+                } catch (_: Exception) {
+                    null
+                }
+                result.success(value)
+            }
         MethodChannel(flutterEngine.dartExecutor.binaryMessenger, "com.stormg.lumadrama/share")
             .setMethodCallHandler { call, result ->
                 if (call.method != "shareText") {