- Updated OpenAPI documentation to include new OAuth2 usage types: `send_api`.
- Added endpoints for issuing one-click unsubscribe tokens in both single and batch requests.
- Modified OAuth client creation and management to enforce new usage types and redirect URI requirements.
- Implemented logic in the Newsletter service to handle one-click unsubscribe token issuance.
- Updated UI to reflect changes in OAuth client usage options and redirect URI handling.
- Enhanced token generation logic to support new scopes and audience settings for Send Engine.
- Added EmailBlacklist service and controller for managing blacklisted emails.
- Created EmailBlacklistDto for data transfer and EmailBlacklistFormViewModel for form handling.
- Implemented views for listing and adding emails to the blacklist.
- Updated database schema with new EmailBlacklist entity and related migrations.
- Enhanced OAuthClientFormViewModel to include ClientId and ClientSecret properties.
- Added EmailBlacklistService to handle email blacklisting logic.
- Integrated email blacklist service into the application with necessary dependencies.
