Refactor: Replace EmailAccountDto with EmailAccount

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.

tests/DigitalData.MessagingService.Tests/Integration/SendingEmailPublisherTests.cs

@@ -5,6 +5,7 @@ using DigitalData.MessagingService.RabbitMQ;
 using Microsoft.Extensions.DependencyInjection;
 using DigitalData.MessagingService.Application.Common.Dto;
 using DigitalData.MessagingService.Application.Common.Interfaces;
+using DigitalData.MessagingService.Domain.Entities;
 
 namespace DigitalData.MessagingService.Tests.Integration;
 
@@ -38,7 +39,7 @@ public sealed class SendingEmailPublisherTests : IAsyncDisposable
             Id = Guid.NewGuid(),
             Mail = new EmailContext
             {
-                Sender = new EmailAccountDto { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
+                Sender = new EmailAccount { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
                 Recipients = ["test@example.com"],
                 Subject = "Integration Test - EnqueueAsync",
                 Body = "<p>Hello from integration test.</p>",
@@ -67,8 +68,8 @@ public sealed class SendingEmailPublisherTests : IAsyncDisposable
             Id = Guid.NewGuid(),
             Mail = new EmailContext
             {
-                Sender = new EmailAccountDto { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
-                Recipients = new List<string> { $"recipient{i}@example.com" },
+                Sender = new EmailAccount { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
+                Recipients = [$"recipient{i}@example.com"],
                 Subject = $"Integration Test - Batch #{i}",
                 Body = $"Batch message {i}",
                 IsHtml = false,
@@ -94,7 +95,7 @@ public sealed class SendingEmailPublisherTests : IAsyncDisposable
             Id = Guid.NewGuid(),
             Mail = new EmailContext
             {
-                Sender = new EmailAccountDto { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
+                Sender = new EmailAccount { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
                 Recipients = ["depth-test@example.com"],
                 Subject = "Integration Test - GetQueueDepth",
                 Body = "Queue depth test",
@@ -121,7 +122,7 @@ public sealed class SendingEmailPublisherTests : IAsyncDisposable
             Id = id,
             Mail = new EmailContext
             {
-                Sender = new EmailAccountDto { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
+                Sender = new EmailAccount { Username = "test@example.com", Password = "password", SmtpServer = "smtp.example.com" },
                 Recipients = new List<string> { "serialize@example.com" },
                 Subject = "Serialization Test",
                 Body = "<strong>Bold</strong>",