- Added HTTP client configuration for SendGrid in Program.cs.
- Cleaned up appsettings files for development and production environments.
- Modified MailingService to use IHttpClientFactory for SendGrid.
- Enhanced NewMailings component with cancel functionality and confirmation dialog.
- Updated project dependencies in .csproj and created package-lock.json.
- Added new methods for creating mailings and testing targets.
- Updated configuration files for JWT settings and connection strings.
- Introduced new DTOs for target column updates and test targets.
- Enhanced MailingStatistic with a new SentDate property.
- Created new components for handling cancelled mailings and target samples.
- Refactored authentication in Login.tsx to use fetch API.
- Updated various services and repositories to support new functionalities.
