feat(tasks): adopt canonical task statuses

api/routers/reconciliation.py

@@ -17,6 +17,7 @@ from api.services.lifecycle import (
     transition_task_status,
     transition_workstream_status,
 )
+from api.task_status import TERMINAL_TASK_STATUSES
 from api.services.reconciliation import (
     ReconciliationClass,
     StateChangeClassification,
@@ -52,7 +53,7 @@ def _conflict(reason: str, follow_up: str) -> StateChangeClassification:
 async def _workstream_tasks_terminal(session: AsyncSession, workstream_id: uuid.UUID) -> bool:
     result = await session.execute(select(Task.status).where(Task.workstream_id == workstream_id))
     statuses = [status_value(row[0]) for row in result.all()]
-    return bool(statuses) and all(status in {"done", "cancelled"} for status in statuses)
+    return bool(statuses) and all(status in TERMINAL_TASK_STATUSES for status in statuses)
 
 
 def _deferred_message(