Adopt the new shadcn-ui registry and cli functionality

Hi, I've created https://github.com/kodehort/shadcn-solid-registry-template a port of the shadcn registry template ported to solid-start. This would enable the distribution of shadcn-solid using the new shadcn cli that supports multiple remote repositories and it framework agnostic. It would also enable you to add the shadcn-solid registry to the new public directory.