refactor(admin): migrate users list to new architecture
- Add UserListController (GET /admin/users[/by-nick|/by-ip]) backed by GetUserListUseCase + UserListResultDTO
- Add UserListSort enum (whitelisted sort columns) and UserListRepositoryInterface + EloquentUserListRepository (paginate preg=1)
- Reuse AdminUserRowMapper for table rows; paginate via Tools::displayPagination + PageMeta
- Remove legacy includes/userlist.php and its $actions entry; point both sidebars to /admin/users
- Pagination total now counts approved users only (matches the listed set), fixing the legacy count-all mismatch
- Add UserListSort enum (whitelisted sort columns) and UserListRepositoryInterface + EloquentUserListRepository (paginate preg=1)
- Reuse AdminUserRowMapper for table rows; paginate via Tools::displayPagination + PageMeta
- Remove legacy includes/userlist.php and its $actions entry; point both sidebars to /admin/users
- Pagination total now counts approved users only (matches the listed set), fixing the legacy count-all mismatch