feat: implement useSingleFlight hook to prevent duplicate async actions and optimize request handling

feat: enhance ChatPanel to directly send suggestions and improve currency handling in math functions

feat: integrate KaTeX for math rendering in chat messages

feat: improve user feedback during API wake-up and enhance error handling for cold starts

feat: enhance API base URL handling and production build validation

feat: enhance PDF ingestion with document fingerprinting and revision handling

feat: implement PDF upload validation to prevent empty and invalid files

feat: implement staggered animations for lists and enhance accessibility with motion preferences

feat: initialize frontend with React, Vite, and Tailwind CSS