fix: remove hardcoded token and use env var

app.py

@@ -10,17 +10,20 @@ DEFAULT_API_URL = "https://agents-course-unit4-scoring.hf.space"
 
 # --- Basic Agent Definition ---
 # ----- THIS IS WERE YOU CAN BUILD WHAT YOU WANT ------
-from smolagents import CodeAgent, HfApiModel, DuckDuckGoSearchTool
+from smolagents import CodeAgent, LiteLLMModel, DuckDuckGoSearchTool
 
 class BasicAgent:
-    def __init__(self):
-        # 使用免費的 AI 模型，並裝上 Google 搜尋工具
-        self.model = HfApiModel(model_id="Qwen/Qwen2.5-72B-Instruct")
+    def __init__(self):        
+        hf_token = os.getenv("HF_TOKEN")
+        
+        self.model = LiteLLMModel(
+            model_id="huggingface/Qwen/Qwen2.5-72B-Instruct",
+            token=hf_token  # 帶入讀取到的變數
+        )
         self.search_tool = DuckDuckGoSearchTool()
         self.agent = CodeAgent(tools=[self.search_tool], model=self.model)
 
     def __call__(self, question: str) -> str:
-        # 讓 AI 開始自動查資料、思考並回答
         try:
             return str(self.agent.run(question))
         except Exception as e: