many fixes and improvements - rework for modules/ and common/

feat(emailer): add Postmark and Resend providers

backend/Infrastructure/Emailer/Services/PostmarkEmailSender.cs

@@ -0,0 +1,37 @@
+using Hutopy.Infrastructure.Emailer.Configuration;
+using Hutopy.Infrastructure.Emailer.Contracts;
+using Microsoft.Extensions.Options;
+using PostmarkDotNet;
+
+namespace Hutopy.Infrastructure.Emailer.Services;
+
+public class PostmarkEmailSender : IEmailSender
+{
+    private readonly PostmarkClient _client;
+    private readonly EmailerOptions _options;
+
+    public PostmarkEmailSender(IOptions<EmailerOptions> options)
+    {
+        _options = options.Value;
+        _client = new PostmarkClient(_options.ApiKey);
+    }
+
+    public async Task SendEmailAsync(string email, string subject, string message)
+    {
+        PostmarkResponse? sendResult = await _client.SendMessageAsync(new PostmarkMessage
+        {
+            From = _options.FromEmail,
+            To = email,
+            Subject = subject,
+            HtmlBody = message,
+            TrackOpens = true,
+            MessageStream = "outbound" // Optional: use "broadcast" for bulk
+        });
+
+        if (sendResult.Status != PostmarkStatus.Success)
+        {
+            throw new InvalidOperationException(
+                $"Postmark failed to send email: {sendResult.Message}");
+        }
+    }
+}