Changed to gemini 2.5 flash

backend/intelligence/llm_client.py

@@ -40,7 +40,7 @@ class GeminiClient(BaseLLMClient):
     def __init__(self, api_key: str):
         import google.generativeai as genai
         genai.configure(api_key=api_key)
-        self.model = genai.GenerativeModel('gemini-1.5-flash')
+        self.model = genai.GenerativeModel('gemini-2.5-flash')
     
     def _generate(self, prompt: str, as_json: bool = False) -> str:
         """Generate response from Gemini."""