feat: improve graph visualization, stabilize multi-hop path reasoning, and update multi-hop page styling

fix: resolve graph edges rendering, fallback query search, community generation timeouts, query session persistence, and new chat functionality

Fix: Resolve 0-entity extraction error by adding NVIDIA LLM integration and robust error handling

feat: complete frontend and backend integration and security configurations

feat: implement GraphRAG Phase 1 backend service layer and test suite

initialise the Graphrag knowledge ai