chore: add ast-grep rule to convert Optional[T] to T | None (#25560)

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

api/core/entities/knowledge_entities.py

@@ -1,11 +1,9 @@
-from typing import Optional
-
 from pydantic import BaseModel
 
 
 class PreviewDetail(BaseModel):
     content: str
-    child_chunks: Optional[list[str]] = None
+    child_chunks: list[str] | None = None
 
 
 class QAPreviewDetail(BaseModel):
@@ -16,4 +14,4 @@ class QAPreviewDetail(BaseModel):
 class IndexingEstimate(BaseModel):
     total_segments: int
     preview: list[PreviewDetail]
-    qa_preview: Optional[list[QAPreviewDetail]] = None
+    qa_preview: list[QAPreviewDetail] | None = None