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

feat(emailer): add Postmark and Resend providers

backend/Modules/Tipping/Models/TipReceivedModel.cs

@@ -0,0 +1,11 @@
+namespace Hutopy.Modules.Tipping.Models;
+
+[PublicAPI]
+public record struct TipReceivedModel(
+    Guid Id,
+    DateTimeOffset CreatedAt,
+    Guid TipperId,
+    string TipperName,
+    decimal Amount,
+    string Currency,
+    string Message);