Fix Flutter transaction anomaly detection request handling

查看 Flutter 应用的 pubspec.yaml 文件，确保其中列出了 http 包。找到包含 'import "http" as http;' 导入语句的文件，将其更改为 'import "package:http/http.dart" as http;'。然后，找到交易异常检测请求函数，为其添加针对非 2xx 响应、网络错误和 JSON 解析的错误处理。确保 API 基础 URL 是可配置的，或许可以通过环境变量或配置文件实现。通过运行应用并模拟 API 故障来进行测试。

Short summary

Flutter transaction anomaly detection request fails to compile and cannot be reliably exercised because the HTTP client import is invalid and request failures are not handled.

Affected version or release

Not specified in the source report; the affected application is a Flutter app using a development API endpoint.

Installation context

Flutter application using the AI Shield India transaction flow; requests target the development API endpoint at 10.0.2.2:8000.

What happened?

The Flutter application imports the HTTP client as import 'http' as http;, but the code calls http.post. This import does not reference the package library and prevents the app from compiling unless corrected to import 'package:http/http.dart' as http; and the http dependency is declared in pubspec.yaml. After compilation is fixed, the transaction flow should handle non-2xx responses, network and timeout failures, and invalid JSON without crashing. The API base URL should also be configurable for emulator, device, and production environments.

Steps to reproduce

1. Create or open the Flutter application containing the AI Shield transaction flow.
2. Ensure the code contains the HTTP import import 'http' as http; and calls http.post.
3. Run the application or compile the project.
4. After correcting the import, invoke the Test High-Value Transfer action with the development API unavailable or returning an error.
5. Observe the compilation failure or unhandled request/JSON failure.

Expected behavior

The app should compile with the HTTP package configured, send the transaction request successfully when the API is available, and show a user-friendly error when the API returns a non-2xx response, times out, cannot be reached, or returns invalid JSON. The API base URL should be configurable per environment.

Additional context

The original implementation uses http://10.0.2.2:8000/api/v1/detect-anomaly, which is emulator-specific and uses cleartext HTTP. Confirm the Android network-security configuration or migrate the endpoint to HTTPS. The request includes user ID, amount, current and previous locations, and screen-sharing state.