Updated api/core/rag/retrieval/dataset_retrieval.py to set user_from via UserFrom, so dataset query attribution aligns with the enum used elsewhere in the codepath.

fix(api): use UserFrom enum for dataset retrieval user_from

Tests not run (not requested).

1) `make lint`
2) `make type-check`
3) `uv run --project api --dev dev/pytest/pytest_unit_tests.sh`

api/core/rag/retrieval/dataset_retrieval.py

@@ -63,6 +63,7 @@ from libs.json_in_md_parser import parse_and_check_json_markdown
 from models import UploadFile
 from models.dataset import ChildChunk, Dataset, DatasetMetadata, DatasetQuery, DocumentSegment, SegmentAttachmentBinding
 from models.dataset import Document as DatasetDocument
+from models.enums import UserFrom
 from services.external_knowledge_service import ExternalDatasetService
 
 default_retrieval_model: dict[str, Any] = {
@@ -176,7 +177,9 @@ class DatasetRetrieval:
         )
 
         all_documents = []
-        user_from = "account" if invoke_from in {InvokeFrom.EXPLORE, InvokeFrom.DEBUGGER} else "end_user"
+        user_from = (
+            UserFrom.ACCOUNT if invoke_from in {InvokeFrom.EXPLORE, InvokeFrom.DEBUGGER} else UserFrom.END_USER
+        )
         if retrieve_config.retrieve_strategy == DatasetRetrieveConfigEntity.RetrieveStrategy.SINGLE:
             all_documents = self.single_retrieve(
                 app_id,