refactor(login): 优化人脸识别登录页面的串口操作实现

- 使用正确的实例引用调用PlcHelper的openSerialPort方法
- 在activity销毁时添加串口资源释放操作
- 改进代码格式化以提高可读性
- 确保串口资源在页面关闭时得到正确清理

app/src/main/java/com/sw/platecabinet/activity/LoginByFaceActivity.kt

@@ -94,7 +94,8 @@ class LoginByFaceActivity : BaseActivity<ActivityLoginFaceBinding>(),
     override fun initialize() {
         userViewModel.activeEngine()
 
-        PlcHelper.getInstance(this).openSerialPort(object : PlcCallback<String> {
+        PlcHelper.getInstance(this@LoginByFaceActivity)
+            .openSerialPort(object : PlcCallback<String> {
                 override fun onSuccess(result: String) {
                     ToastUtils.showToast("打开串口 → 成功: ${result}")
                 }
@@ -480,6 +481,8 @@ class LoginByFaceActivity : BaseActivity<ActivityLoginFaceBinding>(),
 
         recognizeViewModel.destroy()
 
+        PlcHelper.getInstance(this@LoginByFaceActivity).release()
+
         EventBus.getDefault().unregister(this)
         super.onDestroy()
     }