Fix: Update Gemini model to stable gemini-1.5-flash

ai_agent.py

@@ -9,7 +9,7 @@ def get_llm_response(prompt: str, provider: str, cfg: dict) -> str:
     """Invoca o provedor de LLM configurado."""
     if provider == "gemini":
         api_key = cfg.get("gemini_api_key") or os.getenv("GEMINI_API_KEY")
-        url = f"https://generativelanguage.googleapis.com/v1beta/models/gemini-2.0-flash:generateContent?key={api_key}"
+        url = f"https://generativelanguage.googleapis.com/v1beta/models/gemini-1.5-flash:generateContent?key={api_key}"
         payload = {"contents": [{"parts": [{"text": prompt}]}]}
         res = requests.post(url, json=payload)
         if res.status_code == 200: