feat: persistent question caching and track token usage

feat: implement backend chat streaming route and frontend chat interface with RAG integration

feat: initialize chat frontend with stream-based chat window and message UI components

feat: implement streaming RAG chat endpoint and frontend integration with Groq LLM

feat: implement BM25 search index and integrate chat interface with document management API

feat: initialize frontend project with chat, document list, and evaluation panels

feat: initialize project scaffolding with hybrid RAG pipeline and frontend UI structure