fix: slidespeak text output is not the download link (langgenius#10997)

Author: fdb02983rhy

api/core/tools/provider/builtin/slidespeak/tools/slides_generator.py

@@ -149,7 +149,7 @@ async def async_invoke():
                     presentation_bytes = await self._fetch_presentation(session, download_url)
 
                 return [
-                    self.create_text_message("Presentation generated successfully"),
+                    self.create_text_message(download_url),
                     self.create_blob_message(
                         blob=presentation_bytes,
                         meta={"mime_type": "application/vnd.openxmlformats-officedocument.presentationml.presentation"},