feat: implement mvp with email-first login flow and langgraph architecture

tests/test_llm_factory_callbacks.py

@@ -0,0 +1,19 @@
+import pytest
+from langchain_openai import ChatOpenAI
+from ea_chatbot.config import LLMConfig
+from ea_chatbot.utils.llm_factory import get_llm_model
+from langchain_core.callbacks import BaseCallbackHandler
+
+class MockHandler(BaseCallbackHandler):
+    pass
+
+def test_get_llm_model_with_callbacks(monkeypatch):
+    """Test that callbacks are passed to the model."""
+    monkeypatch.setenv("OPENAI_API_KEY", "dummy")
+    config = LLMConfig(provider="openai", model="gpt-4o")
+    handler = MockHandler()
+    
+    model = get_llm_model(config, callbacks=[handler])
+    
+    assert isinstance(model, ChatOpenAI)
+    assert handler in model.callbacks