[batoto] use 'chapter_id' in default archive IDs (#6835)

instead of '{chapter}{chapter_minor}' since some chapters have no actual
chapter number and end up as '0', potentially causing ID overlap

gallery_dl/extractor/batoto.py

@@ -67,6 +67,7 @@ def request(self, url, **kwargs):
 
 class BatotoChapterExtractor(BatotoBase, ChapterExtractor):
     """Extractor for batoto manga chapters"""
+    archive_fmt = "{chapter_id}_{page}"
     pattern = BASE_PATTERN + r"/(?:title/[^/?#]+|chapter)/(\d+)"
     example = "https://xbato.org/title/12345-MANGA/54321"