Web界面预处理提示无可用的特征提取模型

**Summary[问题简述（一句话）]**
Web界面的预处理功能提示无可用的特征提取模型，查看代码发现是ppg_extractor\saved_models文件夹下无可用的模型文件。是否需要执行其他脚本生成？

**Env & To Reproduce[复现与环境]**
win10，6月25日拉取的新版本

**Screenshots[截图（如有）]**
If applicable, add screenshots to help

Start by inspecting the Web preprocessing flow and the ppg_extractor\saved_models directory mentioned in the report. Determine whether the feature-extraction model should be bundled or generated by another script, then verify the Web interface no longer reports that no model is available on the reported Windows setup.

Written by the indexing model from the issue text.