Without this, a non-admin hitting /api/v1/library/stats would see
every other user's active SourceRoot path in the response (e.g.
muli would see /nextcloud-users/admin/files/Photos). Cross-user
visibility into Nextcloud paths is a small info leak in a multi-user
setup. Admins still get the global list when they pass scope=global.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>