Service refactor (#153)

* remove email out of register service

* Update auth service, move JWT handling out of controller

* add docker config for service auth test

* Update mock email system

* Format: ./src/Core/Service

* Refactor authentication payloads and services for registration and login processes

* Format: src/Core/API, src/Core/Service

src/Core/API/API.Specs/Mocks/MockEmailProvider.cs

@@ -0,0 +1,68 @@
+using Infrastructure.Email;
+
+namespace API.Specs.Mocks;
+
+/// <summary>
+/// Mock email provider for testing that doesn't actually send emails.
+/// Tracks sent emails for verification in tests if needed.
+/// </summary>
+public class MockEmailProvider : IEmailProvider
+{
+    public List<SentEmail> SentEmails { get; } = new();
+
+    public Task SendAsync(
+        string to,
+        string subject,
+        string body,
+        bool isHtml = true
+    )
+    {
+        SentEmails.Add(
+            new SentEmail
+            {
+                To = [to],
+                Subject = subject,
+                Body = body,
+                IsHtml = isHtml,
+                SentAt = DateTime.UtcNow,
+            }
+        );
+
+        return Task.CompletedTask;
+    }
+
+    public Task SendAsync(
+        IEnumerable<string> to,
+        string subject,
+        string body,
+        bool isHtml = true
+    )
+    {
+        SentEmails.Add(
+            new SentEmail
+            {
+                To = to.ToList(),
+                Subject = subject,
+                Body = body,
+                IsHtml = isHtml,
+                SentAt = DateTime.UtcNow,
+            }
+        );
+
+        return Task.CompletedTask;
+    }
+
+    public void Clear()
+    {
+        SentEmails.Clear();
+    }
+
+    public class SentEmail
+    {
+        public List<string> To { get; init; } = new();
+        public string Subject { get; init; } = string.Empty;
+        public string Body { get; init; } = string.Empty;
+        public bool IsHtml { get; init; }
+        public DateTime SentAt { get; init; }
+    }
+}