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

feat(emailer): add Postmark and Resend providers

backend/Modules/Memberships/Data/Payment.cs

@@ -0,0 +1,13 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace Hutopy.Modules.Memberships.Data;
+
+public class Payment
+{
+    public Guid Id { get; set; }
+    public DateTimeOffset CreatedAt { get; set; }
+    public decimal Amount { get; set; }
+    [MaxLength(8)] public required string Currency { get; set; }
+    [MaxLength(2048)] public required string InvoiceUrl { get; set; }
+    
+}