Remove provider constraint, let HF route automatically

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app.py

@@ -18,7 +18,6 @@ class BasicAgent:
         print("BasicAgent initialized.")
         model = InferenceClientModel(
             model_id="Qwen/Qwen2.5-72B-Instruct",
-            provider="hf-inference",
             token=os.getenv("HF_TOKEN"),
         )
         self.agent = CodeAgent(