feat: GraphRAG trait

- [x] I have looked for existing issues (including closed) about this

## Feature Request

[What is Graph RAG?](https://neo4j.com/blog/genai/what-is-graphrag/)

### Motivation

Graph RAG is a highly advanced technique used by many different modern workflows. We should try to ensure we adopt Graph RAG in the library as it's quite powerful.

### Proposal

tbd

The issue mentions GraphRAG as a trait but provides no concrete proposal. Research would start by understanding the existing codebase structure for traits and AI/LLM modules, reading about Graph RAG from the linked Neo4j article, and determining how to integrate such a feature into the library's architecture. 'Done' would be a design proposal or implementation of a GraphRAG trait, but the issue gives no starting point.

Scritto dal modello di indicizzazione a partire dal testo della issue.