refactor(get_news_from_newsnow): 改用流式处理解析网页内容

将原有的直接转换响应内容改为流式读取字节流并传入参数，适配MarkItDown的convert_stream接口，优化大内容处理时的内存占用

main/xiaozhi-server/plugins_func/functions/get_news_from_newsnow.py

@@ -1,6 +1,7 @@
 import random
 import httpx
-from markitdown import MarkItDown
+from io import BytesIO
+from markitdown import MarkItDown, StreamInfo
 from config.logger import setup_logging
 from plugins_func.register import register_function, ToolType, ActionResponse, Action
 from typing import TYPE_CHECKING
@@ -144,7 +145,14 @@ async def fetch_news_detail(url):
 
         # 使用MarkItDown清理HTML内容
         md = MarkItDown(enable_plugins=False)
-        result = md.convert(response)
+        result = md.convert_stream(
+            BytesIO(response.content),
+            stream_info=StreamInfo(
+                mimetype="text/html",
+                extension=".html",
+                charset=response.encoding or "utf-8",
+            ),
+        )
 
         # 获取清理后的文本内容
         clean_text = result.text_content