bump to newest langchain packages

rag.py

@@ -1,4 +1,4 @@
-# rag.py  (v4 – imports that actually exist today)
+# rag.py  (v5 – imports that exist in newest wheels)
 from __future__ import annotations
 import os, uuid, tempfile, requests, shutil, re
 from pathlib import Path
@@ -9,7 +9,7 @@ from langchain.text_splitter import RecursiveCharacterTextSplitter
 from langchain_community.vectorstores import FAISS
 from langchain_huggingface import HuggingFaceEmbeddings, HuggingFaceEndpoint
 from langchain_core.prompts import PromptTemplate
-from langchain.chains import RetrievalQA
+from langchain.chains import RetrievalQA          # ← this path exists today
 from supabase import create_client
 
 # ---------- config ----------

requirements.txt

@@ -5,6 +5,6 @@ langchain-huggingface
 sentence-transformers
 faiss-cpu
 datasets
-supabase
+supabase>=2.6
 python-dotenv
 gunicorn