返回数据解析bug

### Describe the bug

返回数据是bease64数据没有自动解码，其他api工具是支持的

### Environment

当前最新版本

No source file, test, or entry point is named. Reproduce the reported case in the current Postcat version using a response containing Base64 data, then locate the response-parsing path and compare its behavior with the issue's expected automatic decoding. Done means the response is decoded automatically without breaking other response formats.

Written by the indexing model from the issue text.