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

feat(emailer): add Postmark and Resend providers

backend/Modules/Memberships/Handlers/GetMembershipTiers.cs

@@ -0,0 +1,52 @@
+using Hutopy.Modules.Memberships.Data;
+
+namespace Hutopy.Modules.Memberships.Handlers;
+
+[PublicAPI]
+public record GetMembershipTiersRequest
+{ 
+    public Guid CreatorId { get; set; }
+}
+
+[PublicAPI]
+public record struct TierModel(
+    Guid Id,
+    DateTimeOffset CreatedAt,
+    string Name,
+    string Description,
+    decimal Price,
+    string CurrencyCode,
+    string StripeProductId);
+
+[PublicAPI]
+public class GetMembershipTiersEndpoint(
+    MembershipsDbContext dbContext)
+    : Endpoint<GetMembershipTiersRequest, List<TierModel>>
+{
+    public override void Configure()
+    {
+        Get("/api/memberships/tiers/{CreatorId:guid}");
+        Options(o => o.WithTags("Memberships"));
+        AllowAnonymous();
+    }
+
+    public override async Task HandleAsync(
+        GetMembershipTiersRequest req,
+        CancellationToken ct)
+    {
+        var tiers = await dbContext
+            .MembershipTiers
+            .Where(tier => tier.CreatorId == req.CreatorId)
+            .Select(tier => new TierModel(
+                tier.Id,
+                tier.CreatedAt,
+                tier.Name,
+                tier.Description,
+                tier.Price,
+                tier.CurrencyCode,
+                tier.StripeProductId))
+            .ToListAsync(ct);
+
+        await SendOkAsync(tiers, ct);
+    }
+}