re-add langchain ecosystem

requirements.txt

@@ -1,30 +1,32 @@
 # core libs (HF image already provides torch & transformers)
-pydantic>=2.0.0
 numpy>=1.24.0
 pandas>=2.0.0
+pydantic>=2.0.0
+python-dotenv>=1.0.0
 
 # embeddings / sentence encoders
+google-genai==1.52.0
 FlagEmbedding==1.3.5
 sentence-transformers>=2.2.2
 
 # UI
+plotly
 streamlit>=1.28.0,<1.36
 
-# LangChain: use latest 0.2.x series compatible with Python 3.8
+# LangChain ecosystem
 langchain>=0.2.17,<0.3
+langchain-core>=0.2.43
+langchain-openai>=0.1.9,<0.3
+langchain-community>=0.2.17,<0.3
 
 # Integration clients / helpers
-qdrant-client>=1.7.0
-python-dotenv>=1.0.0
-openai>=1.0.0
 pyyaml>=6.0
 tqdm>=4.65.0
+openai>=1.0.0
+qdrant-client>=1.7.0
 snowflake-connector-python==3.14.0
 
 
-plotly
-google-genai
-
 # Document / ColPali deps
 # colpali-engine>=0.3.5
 # pdf2image==1.15.0