[Bug] In rag_web_demo. Unable to get the latest Settings of the configuration file after ui refresh

### Bug Type (问题类型)

rest-api (结果不合预期)

### Before submit

- [X] I had searched in the [issues](https://github.com/apache/incubator-hugegraph-ai/issues) and found no similar issues.

### Environment (环境信息)

- `hugegraph_llm.demo.rag_demo.app`

### Expected & Actual behavior (期望与实际表现)

After the process is started (the process is still running), you can refresh the ui after modifying the information in the configuration file locally to display the locally updated parameter information in the configuration file

### Solve the problem-PR

- Fix graph config & prompt config PR: #90
- (TODO) LLM & Embedding & Reranker config