feat: add payment notifications and entitlement fulfillment

Tiku.Application/Commerce/CommerceModels.cs

@@ -64,6 +64,13 @@ public sealed record CurrentEntitlementItem(
     string Status,
     int? DaysLeft);
 
+public sealed record PaymentNotificationProcessResult(
+    string Provider,
+    string EventId,
+    string OrderNo,
+    string Status,
+    bool Idempotent);
+
 public interface ICommerceService
 {
     Task<CommerceOrderItem> CreateOrderAsync(
@@ -89,6 +96,14 @@ public interface ICommerceService
     Task<CurrentEntitlementItem> GetCurrentEntitlementAsync(
         CommerceActor actor,
         CancellationToken cancellationToken = default);
+
+    Task<PaymentNotificationProcessResult> ProcessPaymentNotificationAsync(
+        Guid tenantId,
+        string provider,
+        IReadOnlyDictionary<string, string> headers,
+        string rawBody,
+        JsonElement body,
+        CancellationToken cancellationToken = default);
 }
 
 public sealed class CommerceException(string message, string code) : Exception(message)