add requirements.txt

requirements.txt

@@ -0,0 +1,9 @@
+langchain>=0.3.0
+langchain-chroma>=0.1.0
+langchain-ollama>=0.1.0
+langchain-openai>=0.3.0
+langchain-core>=0.3.0
+langgraph>=0.2.0
+chromadb>=0.4.0
+httpx>=0.27.0
+python-dotenv>=1.0.0