feat: add batch AI re-organize for transfer history and search result recommendation

- Implement batch AI re-organize endpoint for transfer history with progress tracking
- Add batch_manual_transfer_redo system task template and prompt generation
- Refactor agent_manager to support generic background prompt execution
- Add AIRecommendChain for search result recommendation using agent background prompt
- Update search endpoints to use new AIRecommendChain and remove legacy code
- Enhance test cases for batch manual transfer redo
- Minor code cleanup and style fixes

app/schemas/history.py

@@ -1,6 +1,6 @@
 from typing import Optional, Any
 
-from pydantic import BaseModel, ConfigDict
+from pydantic import BaseModel, ConfigDict, Field
 
 
 class DownloadHistory(BaseModel):
@@ -97,3 +97,7 @@ class TransferHistory(BaseModel):
     date: Optional[str] = None
 
     model_config = ConfigDict(from_attributes=True)
+
+
+class BatchTransferHistoryRedoRequest(BaseModel):
+    history_ids: list[int] = Field(default_factory=list)