feat: async pipeline, job queue, generation hardening, and docs

fix: add pypdf and openai as explicit production dependencies

fix: add python-docx to production dependencies

- Replaced timezone.utc with UTC from datetime for consistent datetime handling.

feat: FAISS-only vector store (remove Chroma)

feat(experiment-lab): rewrite RAG pipeline using LangChain framework

fix: apply all bug fixes and improvements (embeddings, cache, postprocess, frontend, tests)

feat: scaffold complete RAG system for RICS-style report generation