- Add #[CoversClass] to Base64Test and FilenameSanitizerTest
- Merge near-duplicate test methods into #[DataProvider] cases across
ResetPasswordControllerTest, SettingsControllerTest, ClaimSeasonCommandTest,
FilenameSanitizerTest, Base64Test, and SeasonRepositoryTest
- Add integration tests for previously untested controllers: public
QuizController (quiz-taking flow), LoginController, RegistrationController,
EliminationController, and PrepareEliminationController
- Add unit tests for Elimination and BankQuestion entity logic
- Extract shared WebTestCase setup/helpers (client, entityManager, login,
entity lookups, CSRF token scraping) into AbstractControllerWebTestCase,
removing duplicated boilerplate from all 14 WebTestCase files
