История коммитов

Split into RegistrationController and ConfirmEmailController.
Extracted user creation and email sending into RegisterUserUseCase.
Added RegistrationFormDTO for passing validated form data.
Email confirmation now uses clean URL /registration/confirm-email.

Split login/logout into separate controllers and routes (/login, /logout).
Extracted login business logic into PerformLoginUseCase returning LoginResultDTO.
Added LoginStatus enum for match-based controller dispatch.
Updated logout links in both themes to /logout.

Switch comments in downloads and library modules from BBCode/WysiBB to
CKEditor. Text is now stored as HTML and sanitized via HTMLPurifier on
save. Message length validation uses EditorContentNormalizer (same
approach as forum) to correctly handle embedded media.

Add converters for existing data:
- install/downloads_comments_converter.php (download__comments)
- install/library_comments_converter.php (cms_library_comments)