fix langchain import path + full filters/fallbacks

rag.py

@@ -1,4 +1,4 @@
-# rag.py  (v2 – with filters + fallbacks)
+# rag.py  (v3 – imports fixed, no more ModuleNotFoundError)
 from __future__ import annotations
 import os, uuid, tempfile, requests, shutil, re
 from pathlib import Path
@@ -7,10 +7,9 @@ from typing import List, Tuple
 from datasets import load_dataset
 from langchain_text_splitters import RecursiveCharacterTextSplitter
 from langchain_community.vectorstores import FAISS
-from langchain_huggingface import HuggingFaceEmbeddings
+from langchain_huggingface import HuggingFaceEmbeddings, HuggingFaceEndpoint
 from langchain_core.prompts import PromptTemplate
-from langchain.chains import RetrievalQA
-from langchain_huggingface import HuggingFaceEndpoint
+from langchain.chains.retrieval_qa.base import RetrievalQA  # ← correct path
 from supabase import create_client
 
 # ---------- config ----------
@@ -120,7 +119,7 @@ def get_llm():
     )
 
 PROMPT = PromptTemplate.from_template("""You are Amina, assistant for {company}.
-Use only the context below. If unsure, say: “A human agent will follow up.”
+Use only the context below. If unsure, say: "A human agent will follow up."
 Context: {context}
 Question: {question}
 Answer:""")