chore: remove legacy files and scripts no longer part of the main architecture

chore: remove deprecated files and add legacy directory to .dockerignore

feat: implement zero-RAM SQLite architecture for Hugging Face deployment

feat: implement full RecSys pipeline (recall, ranking, API)

feat: implement RAG chat with BYOK and Ollama support

feat: advanced RAG architecture with SFT data pipeline

feat: add real-time book cover fetching and client-server architecture