- Add LibraryTestData struct to TestDeviceSetup
- Implement CreateLibrary() for proper library creation in tests
- Implement CreateCollection() for test collection support
- Improve test isolation with dedicated library creation
This provides a more robust foundation for integration tests that need
proper library management support.
- Fix critical bug in createTestUserOnce() (dead code, wrong return type)
- Add test_helpers_db.go with 6 new helper functions
- Impact: All tests can now create users reliably