fix(adapter): 修改 seal 类别为独立类别，以支持 VLM 识别

ocr_tools/universal_doc_parser/models/adapters/pp_doclayout_v3_layout_adapter.py

@@ -77,7 +77,7 @@ class PPDocLayoutV3Detector(BaseLayoutDetector):
         "paragraph_title": "title",
         "reference": "text",
         "reference_content": "text",
-        "seal": "image_body",
+        "seal": "seal",  # 🔧 修改：保留 seal 作为独立类别，用于 VLM 识别
         "table": "table_body",
         "text": "text",
         "vision_footnote": "page_footnote",