### What problem does this PR solve?
When embedding a chatbot, the API returned `"Model Name is required"`.
The embed widget now includes the assistant's `llm_id` as `model_name`
in the completion request.
### Type of change
- [x] Bug Fix
### How has this been tested?
- Created a chatbot with a default model.
- Embedded it and sent a message – the error is gone and the assistant
replies correctly.
### Related Issue
Closes#15883
Co-authored-by: RAGFlow Dev <dev@ragflow.local>
Co-authored-by: Wang Qi <wangq8@outlook.com>
### What problem does this PR solve?
Fix:
- Verify provider with empty llm list in llm_factories.json
- Set search bot's chat_llm_name, use tenant default chat model as
default
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)
### What problem does this PR solve?
Python implementation of the Go-based model_provider API suite.
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
---------
Co-authored-by: bill <yibie_jingnian@163.com>
