Cheng So-mui remembers the days when she was confined within the four white walls of her room in one of Hong Kong’s private residential homes.She was tied to her bed, and tied to her wheelchair, sometimes for days. It was for her own good, she was told, “to prevent self-harm and harm to others”.“It was a bland and meaningless existence,” she said. “Every day was boring and a chore to me to get through.”She said that back then she could not move about, chat with other residents or even ask a…