- Add admin-only users API: list/create/delete (prevent self-delete and last-admin deletion).
- Include is_admin in auth responses.
- Frontend: /admin/users page with table, selection, remove, Add User modal.
- Show “Manage users” in user menu for admins and optional sidebar link.
- Add i18n strings for admin UI.
- Enhance create user script to grant admin via optional third arg.
- Minor: set dev bootstrap user as admin in start script.
The backup script has been updated with the new retention policy:
1. Today's backups: Keeps maximum 4 backups
2. Previous days (within a week): Keeps only the last backup for each day
3. Older than one week: Deletes all backups
