fix: use text_generation instead of chat_completion for Mistral

pipeline/explainer.py

@@ -39,12 +39,12 @@ class FallacyExplainer:
         print(f"FallacyExplainer ready (model: {model_id})")
 
     def _generate_with_prompt(self, prompt_text, max_new_tokens=128):
-        result = self._client.chat_completion(
-            messages=[{"role": "user", "content": prompt_text}],
-            max_tokens=max_new_tokens,
+        return self._client.text_generation(
+            prompt_text,
+            max_new_tokens=max_new_tokens,
             temperature=0.1,
-        )
-        return result.choices[0].message.content.strip()
+            do_sample=True,
+        ).strip()
 
     def _load_prompt(self, path):
         with open(BASE_DIR / path, "r") as f: