Refactor payment request handling to support role change top-ups

- Updated the `PaymentRequest` model to include a new `Kind` property, distinguishing between `Subscription` and `RoleChangeTopUp` requests.
- Modified the `TelegramNotifier` to accommodate the new request type, ensuring accurate notifications for role change top-ups.
- Enhanced the `ConfirmPaymentRequestCommandHandler` to handle role change top-ups without extending the billing period, reflecting the new payment logic.
- Updated various application components and tests to support the new payment request structure and ensure proper functionality.
- Revised API documentation to clarify the behavior of role change top-ups and their impact on billing.

backend/src/PnvPanel.Application/Billing/CreatePaymentRequest/CreatePaymentRequestCommandHandler.cs

@@ -32,9 +32,12 @@ public sealed class CreatePaymentRequestCommandHandler(
         if (profile.MaxConfigs == RoleQuota.Unlimited)
             return Result.Failure<PaymentRequestDto>(BillingErrors.UnlimitedRoleNotSupported);
 
+        // RoleChangeTopUp не считается активной подписной заявкой — доплата за смену роли не должна
+        // мешать пользователю продлить/оформить обычную подписку.
         var hasActiveRequest = await dbContext.PaymentRequests.AnyAsync(
             r =>
                 r.UserId == userId
+                && r.Kind == PaymentRequestKind.Subscription
                 && (
                     r.Status == PaymentRequestStatus.AwaitingPayment
                     || r.Status == PaymentRequestStatus.AwaitingConfirmation

backend/src/PnvPanel.Application/Billing/MarkPaymentSent/MarkPaymentSentCommandHandler.cs

@@ -35,6 +35,7 @@ public sealed class MarkPaymentSentCommandHandler(
         await telegramNotifier.NotifyAdminsPaymentRequestedAsync(
             request.Id,
             profile?.UserName ?? userId.ToString(),
+            request.Kind,
             request.Period,
             request.AmountSnapshot,
             cancellationToken

backend/src/PnvPanel.Application/Billing/PaymentRequestDto.cs

@@ -4,12 +4,13 @@ namespace PnvPanel.Application.Billing;
 
 public sealed record PaymentRequestDto(
     Guid Id,
-    PaymentPeriod Period,
+    PaymentRequestKind Kind,
+    PaymentPeriod? Period,
     int AmountSnapshot,
     PaymentRequestStatus Status,
     DateTimeOffset CreatedAt
 )
 {
     public static PaymentRequestDto FromDomain(PaymentRequest request) =>
-        new(request.Id, request.Period, request.AmountSnapshot, request.Status, request.CreatedAt);
+        new(request.Id, request.Kind, request.Period, request.AmountSnapshot, request.Status, request.CreatedAt);
 }

backend/src/PnvPanel.Application/Billing/SendRequisitesToTelegram/SendRequisitesToTelegramCommandHandler.cs

@@ -38,13 +38,16 @@ public sealed class SendRequisitesToTelegramCommandHandler(
             .FirstOrDefaultAsync(cancellationToken);
 
         var text =
-            $"💳 Реквизиты для оплаты ({PeriodLabel(request.Period)}, {request.AmountSnapshot} ₽):\n{settings?.RequisitesText}";
+            $"💳 Реквизиты для оплаты ({DescribeRequest(request)}, {request.AmountSnapshot} ₽):\n{settings?.RequisitesText}";
 
         await telegramNotifier.NotifyUserAsync(userId, text, null, cancellationToken);
 
         return Result.Success();
     }
 
+    private static string DescribeRequest(PaymentRequest request) =>
+        request.Kind == PaymentRequestKind.RoleChangeTopUp ? "доплата за смену роли" : PeriodLabel(request.Period!.Value);
+
     private static string PeriodLabel(PaymentPeriod period) =>
         period switch
         {