Phase 7b: Embed orderId in callback URL for CustomerPurchasePackage

- CustomerPurchasePackage: append orderId to callback URL before sending to gateway
- Ensures PaymentCallback page receives orderId via query string for verification

src/CMSMicroservice.WebApi/Services/PackageService.cs

@@ -207,13 +207,17 @@ public class PackageService : PackageContract.PackageContractBase
             .Select(u => new { u.Mobile })
             .FirstOrDefaultAsync(context.CancellationToken);
         
+        // Embed orderId in callback URL so FrontOffice can pass it back for verification
+        var separator = request.CallbackUrl.Contains('?') ? "&" : "?";
+        var callbackWithOrder = $"{request.CallbackUrl}{separator}orderId={purchase.Id}";
+        
         var paymentResult = await _paymentGateway.InitiatePaymentAsync(new PaymentRequest
         {
             Amount = package.Price,
             UserId = userId,
             Mobile = user?.Mobile ?? string.Empty,
             Description = $"خرید پکیج {package.Title}",
-            CallbackUrl = request.CallbackUrl
+            CallbackUrl = callbackWithOrder
         }, context.CancellationToken);
         
         if (!paymentResult.IsSuccess)