test(tasks): rewrite API task tests for redesigned model and v9 compat

Replaces the old Django TestCase-based tests with pytest-style classes using
PaperlessTaskFactory. Covers v10 field names, v9 backwards-compat field
mapping, filtering, ordering, acknowledge, acknowledge_all, summary, active,
and run endpoints. Also adds PaperlessTaskFactory to factories.py and fixes
a redundant source= kwarg in TaskSerializerV10.related_document_ids.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/documents/serialisers.py

@@ -2434,7 +2434,6 @@ class TaskSerializerV10(OwnedObjectSerializer):
     related_document_ids = serializers.ListField(
         child=serializers.IntegerField(),
         read_only=True,
-        source="related_document_ids",
     )
     task_type_display = serializers.CharField(
         source="get_task_type_display",

src/documents/tests/factories.py

@@ -11,6 +11,7 @@ from documents.models import Correspondent
 from documents.models import Document
 from documents.models import DocumentType
 from documents.models import MatchingModel
+from documents.models import PaperlessTask
 from documents.models import StoragePath
 from documents.models import Tag
 
@@ -65,3 +66,17 @@ class DocumentFactory(DjangoModelFactory):
     correspondent = None
     document_type = None
     storage_path = None
+
+
+class PaperlessTaskFactory(DjangoModelFactory):
+    class Meta:
+        model = PaperlessTask
+
+    task_id = factory.LazyFunction(lambda: str(__import__("uuid").uuid4()))
+    task_type = PaperlessTask.TaskType.CONSUME_FILE
+    trigger_source = PaperlessTask.TriggerSource.WEB_UI
+    status = PaperlessTask.Status.PENDING
+    input_data = factory.LazyFunction(dict)
+    result_data = None
+    result_message = None
+    acknowledged = False