- Updated `ReadEmailTemplateQuery` to implement `IRequest<ReadEmailTemplateResponse?>`.
- Changed `ReadEmailTemplateResponse` from a record to a class with updated properties.
- Enhanced `EmailTemplateController` to inject `IEmailTemplateRepository` and `IMediator`, and made the `Get` method asynchronous.
- Introduced `ReadEmailTemplateMappingProfile` for AutoMapper mappings.
- Added `ReadEmailTemplateQueryHandler` to manage query logic and response mapping.
These changes improve the structure and maintainability of the email template querying process.