Add ComfyUI

[liangqiyuan]

Description

This PR introduces a ComfyUI integration for LLMRouter, providing a visual, node-based interface for the data generation pipeline. This allows users to intuitively select datasets, configure LLM candidates, and execute the full query generation -> embedding -> routing data pipeline without writing code.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• New router implementation
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Performance improvement
• Code refactoring
• Test addition or update

Changes Made

• Added ComfyUI custom nodes in ComfyUI directory (DatasetSelector, LLMSelector, etc.).
• Created and synchronized llm_router_template.json workflow
• Added detailed installation guides in ComfyUI/README.md.
• Updated the main README.md.

Router Affected (if applicable)

• knnrouter
• svmrouter
• mlprouter
• mfrouter
• elorouter
• routerdc
• automix
• hybrid_llm
• graphrouter
• causallm_router
• router_r1
• gmtrouter
• knnmultiroundrouter
• llmmultiroundrouter
• Other / Core framework

Checklist

• I have tested my changes locally
• I have reviewed my own code
• I have added/updated documentation where necessary
• I have added tests for my changes (if applicable)
• My changes do not introduce new warnings or errors
• Any dependent changes have been merged and published

Test Plan

Run the workflow in ComfyUI by clicking "Run".

Expected Output (Console):

🎉 Processing completed successfully in 424.9 seconds!
📊 Final statistics:
  - Train samples: 749
  - Test samples: 189
  - Unified embeddings: 0
  - Average train performance: 0.3405
  - Average test performance: 0.4127