fix(sdk): add cancel_all_task_of call in stop_parsing endpoint (infiniflow#11748)

## Problem
The SDK API endpoint `DELETE /datasets/{dataset_id}/chunks` only updates
database status but does not send cancellation signal via Redis, causing
background parsing tasks to continue and eventually complete (status
becomes DONE instead of CANCEL).

## Root Cause
The SDK endpoint was missing the `cancel_all_task_of(id)` call that the
web API
([api/apps/document_app.py](cci:7://file:///d:/workspace1/ragflow-admin/api/apps/document_app.py:0:0-0:0))
uses to properly stop background tasks.

## Solution
Added `cancel_all_task_of(id)` call in the
[stop_parsing](cci:1://file:///d:/workspace1/ragflow/api/apps/sdk/doc.py:785:0-855:23)
function to send cancellation signal via Redis, consistent with the web
API behavior.

## Related Issue
Fixes infiniflow#11745

Co-authored-by: tedhappy <tedhappy@users.noreply.github.com>

Author: tedhappy

api/apps/sdk/doc.py

@@ -33,7 +33,7 @@
 from api.db.services.knowledgebase_service import KnowledgebaseService
 from api.db.services.llm_service import LLMBundle
 from api.db.services.tenant_llm_service import TenantLLMService
-from api.db.services.task_service import TaskService, queue_tasks
+from api.db.services.task_service import TaskService, queue_tasks, cancel_all_task_of
 from api.db.services.dialog_service import meta_filter, convert_conditions
 from api.utils.api_utils import check_duplicate_ids, construct_json_result, get_error_data_result, get_parser_config, get_result, server_error_response, token_required, \
     get_request_json
@@ -835,6 +835,8 @@ async def stop_parsing(tenant_id, dataset_id):
             return get_error_data_result(message=f"You don't own the document {id}.")
         if int(doc[0].progress) == 1 or doc[0].progress == 0:
             return get_error_data_result("Can't stop parsing document with progress at 0 or 1")
+        # Send cancellation signal via Redis to stop background task
+        cancel_all_task_of(id)
         info = {"run": "2", "progress": 0, "chunk_num": 0}
         DocumentService.update_by_id(id, info)
         settings.docStoreConn.delete({"doc_id": doc[0].id}, search.index_name(tenant_id), dataset_id)