fix: move BatchDeleteRequest class before its use in endpoint

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/backend/routers/files.py

@@ -169,6 +169,10 @@ async def delete_file(
     return {"message": f"已删除 {filename}"}
 
 
+class BatchDeleteRequest(BaseModel):
+    files: list[dict]
+
+
 @router.post("/batch-delete")
 async def batch_delete_files(
     req: BatchDeleteRequest,
@@ -252,10 +256,6 @@ class RelationDeleteRequest(BaseModel):
     ids: List[int]
 
 
-class BatchDeleteRequest(BaseModel):
-    files: list[dict]
-
-
 def _cleanup_relation_for_deleted_file(directory: str, filename: str):
     """Clean up relation table when a file is deleted."""
     import sqlite3