更新DifyQueryRetrieval类的初始化参数，改为使用环境变量获取API密钥和基础URL；优化意图识别示例中的参数传递；调整问题和回答的格式描述；增加请求超时设置。

rag2_0/dify/dify_client/client.py

@@ -8,7 +8,7 @@ class DifyClient:
         self.api_key = api_key
         self.base_url = base_url
 
-    def _send_request(self, method, endpoint, json=None, params=None, stream=False):
+    def _send_request(self, method, endpoint, json=None, params=None, stream=False, timeout=300):
         headers = {
             "Authorization": f"Bearer {self.api_key}",
             "Content-Type": "application/json",
@@ -16,7 +16,7 @@ class DifyClient:
 
         url = f"{self.base_url}{endpoint}"
         response = requests.request(
-            method, url, json=json, params=params, headers=headers, stream=stream, verify=False
+            method, url, json=json, params=params, headers=headers, stream=stream, verify=False, timeout=timeout
         )
 
         return response