Add climate negotiation LLM example

[BhoomiAgrawal12]

Summary

I built a multi-agent climate treaty negotiation simulation using mesa-llm and am contributing it here as a learning/exploration example for the community. Originally I created it to explore and test mesa-llm's features in a realistic multi-party negotiation setting. It turned out to be a good showcase of several mesa-llm capabilities together, so I thought it would be a useful addition to the llm/ examples directory.

What the model does

Six country agents (USA, EU, China, India, Brazil, Russia), each powered by an LLM, negotiate a shared emissions-reduction target over multiple rounds. A treaty is reached when at least 2/3 of countries formally accept a common proposal.

Mesa-LLM features it demonstrates

• STLTMemory - short-term stores recent proposals; long-term consolidates committed positions
• ReActReasoning - agents reason about economic interests before acting
• speak_to (inbuilt tool) - targeted diplomatic messaging between agents
• Custom @tool functions - make_proposal, accept_proposal, form_coalition, reject_and_counter
• vision=-1 - full-room awareness with no spatial grid
• DataCollector - tracks proposals, acceptances, average pledge, coalition size, treaty status per round