修复子图中 common/intent 等模块的导入路径（已移至 app/core）

backend/app/subgraphs/contact/nodes.py

@@ -8,7 +8,7 @@ from typing import Dict, Any
 from datetime import datetime
 
 # 公共工具
-from ..common import MarkdownFormatter
+from app.core import MarkdownFormatter
 
 from .state import ContactState
 from .api_client import ContactAPIClient

backend/app/subgraphs/dictionary/nodes.py

@@ -8,7 +8,7 @@ from datetime import datetime
 import random
 
 # 公共工具
-from ..common import (
+from app.core import (
     MarkdownFormatter
 )
 

backend/app/subgraphs/news_analysis/nodes.py

@@ -7,7 +7,7 @@ from typing import Dict, Any
 from datetime import datetime
 
 # 公共工具
-from ..common import MarkdownFormatter
+from app.core import MarkdownFormatter
 
 from .state import (
     NewsAnalysisState,