refactor(module): unify config retrieval logic

app/modules/wechat/__init__.py

@@ -71,14 +71,8 @@ class WechatModule(_ModuleBase, _MessageBase[WeChat]):
         :return: 渠道、消息体
         """
         try:
-            # 获取客户端
-            client_config = None
-            if source:
-                client_config = self.get_config(source)
-            else:
-                client_configs = self.get_configs()
-                if client_configs:
-                    client_config = list(client_configs.values())[0]
+            # 获取服务配置
+            client_config = self.get_config(source)
             if not client_config:
                 return None
             client: WeChat = self.get_instance(client_config.name)