Introduced `EmailAccount`, `EmailAttachment`, and `ReceivedEmail`
entities with database mappings using data annotations. These
entities represent email account configurations, attachments,
and received emails, respectively.
Added conditional compilation to ensure compatibility between
.NET and .NET Framework. Updated `DigitalData.MessagingService.Domain.csproj`
to include `System.ComponentModel.DataAnnotations` for `net462`.
Defined relationships between entities, including navigation
properties and foreign key constraints.
Replaced the `EmailAccountDto` class with the `EmailAccount` class across the codebase to consolidate the `EmailAccount` entity into the domain layer. Updated namespaces, method signatures, property types, and test cases to reflect this change.
Moved `EmailAccount` from `DigitalData.MessagingService.Application.Common.Dto` to `DigitalData.MessagingService.Domain.Entities`. Updated XML documentation and removed redundant project file entries. Adjusted namespaces for related queries, validators, and commands to align with the new structure.
These changes improve separation of concerns and align with domain-driven design principles.
