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

feat(emailer): add Postmark and Resend providers

backend/Modules/Creators/Data/Slugs.cs

@@ -0,0 +1,14 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace Hutopy.Modules.Creators.Data;
+
+public class Slugs
+{
+    public Guid Id { get; set; }
+    public Guid CreatedBy { get; set; }
+    public DateTimeOffset CreatedAt { get; init; }
+    public Guid? UsedBy { get; set; }
+    [MaxLength(128)] public string Name { get; set; } = null!;
+    [MaxLength(128)] public string NormalizedName { get; set; } = null!;
+    public DateTimeOffset ReservedUntil { get; set; }
+}