update_task, update_task_status, add_task, add_subtask, set_my_day,
abort_merge, review_task, and their batch variants now return a lean
TaskRefDto (id/listId/title/status/sortOrder/isMyDay) instead of the
full TaskDto. Those tools were re-sending the caller's own description
text back on every call, wasting a large share of session context on
list-handler-style runs. get_task/list_tasks/batch_get_tasks are
untouched and still return the full DTO.