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

fix: graph visualization - HSL color strings need commas for polished parser

fix: set NEXT_PUBLIC_API_URL for production HF Space backend

feat: simplify graph visualization to 3D only, implement 3D camera controls, and persist document states globally

feat: prioritize Groq model, configure LLM fallbacks, and fix graph entity highlighting by name

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