- Fix SetLibraryVisibility request format (library_ids -> library_id)
- Fix UpdateReadingProgress HTTP method (POST -> PUT)
- Fix DeleteMediaNote expected status (200 -> 204)
- Add cleanupTestData() helper for better test cleanup
- Improve Setup_CreateDuplicateTestUsers to handle existing data
- Add graceful handling of 409 and 429 responses
- Update password test to create/delete temporary user
- Add test requirements comment at top of file
These changes improve test reliability and reduce flakiness.