feat: academic citation format with clickable links and access dates

fix: file uploader browse button visible on dark sidebar

feat: add beta disclaimer banner below header

feat: add icons to distinguish PDF vs dataset sources

fix: spinner renders below chat history, 3+2 chip grid for 14-inch screens

feat: searchable knowledge base, centered layout, responsive CSS

fix: sidebar checkbox visibility + LLM falls back to general knowledge

fix: disable Streamlit XSRF protection for HF Spaces proxy

fix: robust Pydantic retriever + friendly error messages in UI

feat: production deployment setup for HF Spaces