Supporting Zhipu AI API

[JasonGuoo]

Added Zhipu AI Support with Example

This PR adds support for Zhipu AI's API and includes a demo example:

Key Changes

Zhipu API Integration:

• Implemented zhipu_complete and zhipu_embedding functions for chat completions and embeddings
• Added proper handling of keyword extraction with JSON format responses
• Implemented robust error handling and response parsing
• Set default model to "glm-4-flashx" for optimal cost/performance balance

Example Usage:

• Added lightrag_zhipu_demo.py demonstrating:
• Basic chat completion

The implementation has been tested with:

• Indexing the book from the main readme.
• Answering questions with 4 query types.

Usage

To use Zhipu AI with LightRAG:

Set ZHIPUAI_API_KEY environment variable
Import and use the provided functions directly or through LightRAG's model interface
Refer to examples/lightrag_zhipu_demo.py for detailed usage examples