Refactor AgentNode in graph.py to utilize CodeAgent instead of ToolCallingAgent, update prompt template loading to use code_agent.yaml, and enhance step callback logging for improved debugging.

Enhance logging in AgentNode's __call__ method in graph.py to track state before and after processing, including detailed information about messages, question, and answer.

Add max_steps parameter to ToolCallingAgent in graph.py for improved agent control

Enhance graph.py to load prompt templates from local file and configure LiteLLM; add new prompt files for tool calling and code agent

Add initial implementation of AgentRunner and agent graph; include .gitignore and update requirements