Client-side LLM selection, multi-model support

[ThreeFish-AI]

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1. Is this request related to a challenge you're experiencing?

Yes, our users hope that the client interface can support choosing the LLM they want to use.

2. Describe the feature you'd like to see

It is expected to add the function of selecting LLM next to the input box similar to the chat bar.

3. How will this feature improve your workflow or experience?

We can experience the differences of multiple LLM versions in one Agent and choose the most appropriate LLM for use according to different scenarios.

4. Additional context or comments

No response

5. Can you help us with this feature?

• [ ] I am interested in contributing to this feature.