Introduced the `EmailAccountSyncWorker` background service to initialize and synchronize email accounts using RabbitMQ for event-driven processing. The service resolves email account configurations from application settings and upserts them into the repository.
Updated `MessagingServiceDbContext` to configure the `EmailAccount` entity, setting the `Username` property to use the `SQL_Latin1_General_CP1_CI_AS` collation for case-insensitive comparisons.
Added necessary `using` directives in `DependencyInjection.cs` to integrate new dependencies for AutoMapper, repositories, services, and background processing.
Added the `Microsoft.EntityFrameworkCore.InMemory` package to enable an in-memory database for testing and lightweight storage. Introduced `MessagingServiceDbContext` with `DbSet` properties for `EmailAccount`, `ReceivedEmail`, and `EmailAttachment`. Configured entity relationships in `OnModelCreating`.
Registered `MessagingServiceDbContext` and a generic repository (`IRepository<>`) in the dependency injection container. Updated namespaces and imports to support the new DbContext and repository.
Improved project structure to enhance modularity and testability by leveraging EF Core's in-memory database.
Reorganized the solution structure to align with a layered architecture:
- Replaced `src` folder with `core`, `infrastructure`, and `presentation`.
- Moved projects to their respective folders.
- Added `DigitalData.MessagingService.Publisher.Abstraction` project.
- Removed `DigitalData.MessagingService.Client` project.
Updated project configurations and nesting in the solution file.
Added `appsettings.Secrets.json` with RabbitMQ and email account settings:
- RabbitMQ configuration includes hostname, port, credentials, and queue/exchange details.
- Email configuration includes SMTP server details and credentials.
