[moz] fix(api): list_tasks 默认排序改为 created_at DESC（最新在前）

src/blackboard/operations.py

@@ -208,7 +208,7 @@ class Blackboard:
                 params.append(parent_task)
             if conditions:
                 query += " WHERE " + " AND ".join(conditions)
-            query += " ORDER BY priority ASC, created_at ASC"
+            query += " ORDER BY priority ASC, created_at DESC"
             rows = conn.execute(query, params).fetchall()
             return [Task.from_row(r) for r in rows]
         finally: