Fix session isolation: scope all queries to session_id

Fix citation links and PDF viewer for HF Spaces via APP_PUBLIC_URL env var

Add conversation history to chat — last 3 exchanges sent to LLM

Fix nginx Connection header for uploads and async httpx for arXiv fetch

Add HuggingFace Spaces deployment + session isolation

Fixed Citation PDF Viewer functionality

Fixed Document Viewer

Fixed fetch from arxiv functionality

Initial commit: Academic Research RAG project