Refactor: Replace EmailAttachmentContext with DTO

Replaced `EmailAttachmentContext` with `EmailAttachmentDto` across the codebase to align with the updated DTO naming convention.

- Renamed `EmailAttachmentContext` to `EmailAttachmentDto`.
- Updated property types, method signatures, and return types to use `EmailAttachmentDto`.
- Modified XML documentation references to reflect the new class name.
- Updated `ReceivedEmailContext` to `ReceivedEmailDto` and adjusted related methods and properties.
- Refactored `FetchEmailsAsync` methods and handlers to use `ReceivedEmailDto`.
- Adjusted `BuildAttachmentsAsync` and attachment handling logic in `EmailController` and `LimilabsImapEmailService`.

This refactor ensures consistency and improves code clarity while maintaining functionality.

src/core/DigitalData.MessagingService.Application/EmailReceiving/Queries/FetchEmailsQuery.cs

@@ -10,7 +10,7 @@ namespace DigitalData.MessagingService.Application.EmailReceiving.Queries;
 /// <summary>
 /// Query to fetch emails from an IMAP mailbox.
 /// </summary>
-public record FetchEmailsQuery : IRequest<IEnumerable<ReceivedEmailContext>>
+public record FetchEmailsQuery : IRequest<IEnumerable<ReceivedEmailDto>>
 {
     /// <summary>
     /// Identifies the email account to use.
@@ -25,9 +25,9 @@ public record FetchEmailsQuery : IRequest<IEnumerable<ReceivedEmailContext>>
 
 public class FetchEmailsQueryHandler(
     ISender Sender,
-    IImapEmailService ImapService) : IRequestHandler<FetchEmailsQuery, IEnumerable<ReceivedEmailContext>>
+    IImapEmailService ImapService) : IRequestHandler<FetchEmailsQuery, IEnumerable<ReceivedEmailDto>>
 {
-    public async Task<IEnumerable<ReceivedEmailContext>> Handle(FetchEmailsQuery request, CancellationToken cancellationToken)
+    public async Task<IEnumerable<ReceivedEmailDto>> Handle(FetchEmailsQuery request, CancellationToken cancellationToken)
     {
         var account = await Sender.Send(request.Account, cancellationToken)
             ?? throw new NotFoundException(