- Fix username conflict: use unique name 'updateduser-admin-test'
- Fix 'last admin' test: explicitly delete regular user and verify admin count
- Add missing Content-Type header to PUT request
- Fix assertion: match actual validator error message ('oneof')
- Update email domain references to @tests.bookhoard.internal
All 5 subtests now pass:
- Admin update username ✓
- Admin promote user to admin ✓
- Try to demote last admin ✓
- Non-admin tries update ✓
- Invalid role ✓