Fix HF_TOKEN: no default value per hackathon checklist

inference.py

@@ -42,7 +42,7 @@ from openenv.core.generic_client import GenericEnvClient
 
 API_BASE_URL = os.environ.get("API_BASE_URL", "https://router.huggingface.co/v1")
 MODEL_NAME = os.environ.get("MODEL_NAME", "gpt-4.1-mini")
-HF_TOKEN = os.environ.get("HF_TOKEN") or os.environ.get("API_KEY", "")
+HF_TOKEN = os.environ.get("HF_TOKEN")
 ENV_URL = os.environ.get("ENV_URL", "http://localhost:7860").rstrip("/")
 
 BENCHMARK = "data_detective"
@@ -64,7 +64,7 @@ TASK_IDS = [
 def _build_llm_client() -> OpenAI:
     if not HF_TOKEN:
         print(
-            "ERROR: Set HF_TOKEN (or API_KEY) for LLM access. Exiting.",
+            "ERROR: Set HF_TOKEN for LLM access. Exiting.",
             file=sys.stderr,
         )
         sys.exit(1)