[bug] model name didn't update in the chat view after model switch

[muxi1998]

after switching the model in setting, the model name should change on the title, but currently didn't work.

[muxi1998]

Fix the issue in #100

[Solution]

• Standardize model name retrieval by using the shared preference

[Validation]

1. After the model is loaded for the first time, check the model name displayed in the title.
2. Navigate to the settings page and select a different model from the list.
3. Return to the chat view.
4. Check the model name again — it should now reflect the most recently selected model.