The TestWorker_SetFoldersJob test was submitting a set folders job without
first registering the folder with the library through the HTTP API. This caused
the job to fail because the folder wasn't properly tracked.
Changes:
- Call addFolderToLibrary before submitting the set folders job
- Ensures the temporary test directory is properly registered with the library
- Aligns test behavior with actual API workflow where folders must be added first