Chat with your docs (simple RAG)

Build a 'chat with your documents' app.

1. Upload markdown/PDF files; extract text; split into ~800-token chunks with overlap.
2. Create embeddings with [PROVIDER] and store them in [pgvector on Supabase / a local SQLite vector extension / an in-memory index for the demo].
3. On a question: embed it, retrieve the top 5 chunks, and answer using ONLY those chunks. If the answer isn't there, say so.
4. Show citations (file name + snippet) under each answer.
5. Keep API keys server-side; limit upload size and file types.
Start with the in-memory version, then swap the store.