- Remove GET /progress/:id and POST /progress/:id from progress routes.
These were superseded by the media-item progress routes. Only
GET /progress/:id/history remains.
- Add ProgressService to router.Config so sync.go can inject it into
KoboHandler via SetProgressService().
- Inject ProgressService into KoboHandler at route registration time
rather than requiring a separate setup step.
- Update comment from 'Legacy progress routes' to 'Progress routes'.