Toggle the completion state of a subtask.
curl -X PATCH http://localhost:3000/api/v1/tasks/subtasks/clsub001/toggle \
-H "Authorization: Bearer <token>"
{
"id": "clsub001",
"title": "Write unit tests",
"completed": true,
"taskId": "clxyz789"
}
curl -X PATCH http://localhost:3000/api/v1/tasks/subtasks/clsub001/toggle \
-H "Authorization: Bearer <token>"
{
"id": "clsub001",
"title": "Write unit tests",
"completed": true,
"taskId": "clxyz789"
}