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

feat(emailer): add Postmark and Resend providers

backend/Modules/Tipping/Services/TipPaymentNotifier.cs

@@ -0,0 +1,31 @@
+using Hutopy.Modules.Tipping.Contracts;
+using Hutopy.Modules.Tipping.Data;
+
+namespace Hutopy.Modules.Tipping.Services;
+
+public class TipPaymentNotifier(
+    TippingDbContext dbContext,
+    ILogger<TipPaymentNotifier> logger)
+    : ITipPaymentNotifier
+{
+    public async Task NotifyPaymentSucceedAsync(
+        string sessionId,
+        string invoiceUrl,
+        CancellationToken ct)
+    {
+        var tip = await dbContext.Tips.SingleOrDefaultAsync(
+            t => t.StripeSessionId == sessionId,
+            cancellationToken: ct);
+
+        if (tip is not null)
+        {
+            tip.Status = TipStatus.Paid;
+            tip.StripeInvoiceUrl = invoiceUrl;
+            await dbContext.SaveChangesAsync(ct);
+        }
+        else
+        {
+            logger.LogError("Tip with session ID {SessionId} not found", sessionId);
+        }
+    }
+}