feat: Refactor to use OpenAI client and improve response handling

feat: Enhance error handling and debugging in response processing

feat: Update AGENTS.md and app.py to support GLM-4.7-Flash provider

refactor: Update import statement for HumanMessage and SystemMessage from langchain_core

feat: Add GLM-4.7 provider support with environment variable authentication

feat: Add Groq API key validation by making an API call and integrate it into the application's login flow.

feat: Implement API key authentication, owner bypass, and rate limiting for the Gradio interface.

Add initial implementation of English writing assistant with Gradio interface and Groq API integration