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

feat: add Screen 4 - Multi-Hop Reasoning page

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

feat: implement 3D visualization toggle and Retrieval Context Preview

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

feat: complete frontend and backend integration and security configurations