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

feat(emailer): add Postmark and Resend providers

backend/Modules/Creators/Features/ChangeEmail.cs

@@ -0,0 +1,67 @@
+using Hutopy.Infrastructure.Security;
+using Hutopy.Modules.Creators.Data;
+
+namespace Hutopy.Modules.Creators.Features;
+
+[PublicAPI]
+public record ChangeEmailRequest(
+    Guid CreatorId,
+    string? Email);
+
+[PublicAPI]
+public sealed class ChangeEmailRequestValidator : Validator<ChangeEmailRequest>
+{
+    public ChangeEmailRequestValidator()
+    {
+        RuleFor(x => x.CreatorId)
+            .NotEmpty()
+            .WithMessage("Creator ID is required");
+
+        RuleFor(x => x.Email)
+            .Must(email => email == null || !string.IsNullOrWhiteSpace(email))
+            .WithMessage("Email cannot be empty if provided");
+    }
+}
+
+[PublicAPI]
+public class ChangeEmailHandler(
+    CreatorsDbContext context)
+    : Endpoint<ChangeEmailRequest>
+{
+    public override void Configure()
+    {
+        Post("/api/creators/{CreatorId}/email");
+        Options(o => o.WithTags("Creators"));
+    }
+
+    public override async Task HandleAsync(
+        ChangeEmailRequest request,
+        CancellationToken ct)
+    {
+        var creator = await context
+            .Creators
+            .Include(c => c.Presentation)
+            .SingleOrDefaultAsync(
+                c => c.Id == request.CreatorId,
+                cancellationToken: ct);
+
+        if (creator is null)
+        {
+            await SendNotFoundAsync(ct);
+            return;
+        }
+
+        // Check if the current user is the creator
+        if (creator.CreatedBy != User.GetUserId())
+        {
+            await SendUnauthorizedAsync(ct);
+            return;
+        }
+
+        creator.Presentation.Email = request.Email?.Trim();
+        
+        await context.SaveChangesAsync(ct);
+        
+        await SendOkAsync(ct);
+    }
+}