Enhance user plan management and update related endpoints

- Added new configuration options for user plans in `.env.example`, including `Plans__MaxCustomConfigCount` and `Plans__MinCustomConfigCount`.
- Introduced `MapPlanEndpoints` in `Program.cs` to handle plan-related API routes.
- Implemented `SetUserPlan` endpoint in `RoleEndpoints` to allow admins to assign plans to users.
- Removed deprecated role request approval endpoints from `AdminSupportEndpoints`.
- Updated `ITelegramNotifier` and related classes to reflect changes in role request handling and payment notifications.
- Refactored role management commands to remove `MaxConfigs` and focus on `MaxIpLimit` and billing settings.
- Enhanced billing request handling to accommodate plan changes instead of role changes.
- Updated various interfaces and command handlers to support new plan management features.

backend/src/PnvPanel.Application/Admin/Billing/ConfirmPaymentRequestCommandHandler.cs

@@ -48,7 +48,7 @@ public sealed class ConfirmPaymentRequestCommandHandler(
 
         var (request, newPaidUntil) = claimed.Value;
 
-        // RoleChangeTopUp — доплата разницы в цене при апгрейде роли, не покупка времени: подтверждение
+        // PlanChangeTopUp — доплата разницы в цене при увеличении тарифа, не покупка времени: подтверждение
         // не возвращает Expired-конфиги (это делает обычная Subscription-оплата/продление).
         if (request.Kind == PaymentRequestKind.Subscription)
         {
@@ -75,8 +75,8 @@ public sealed class ConfirmPaymentRequestCommandHandler(
         );
 
         var message =
-            request.Kind == PaymentRequestKind.RoleChangeTopUp
-                ? "✅ Доплата за смену роли подтверждена."
+            request.Kind == PaymentRequestKind.PlanChangeTopUp
+                ? "✅ Доплата за смену тарифа подтверждена."
                 : $"✅ Оплата подтверждена. Доступ продлён до {newPaidUntil:dd.MM.yyyy}.";
         await telegramNotifier.NotifyUserAsync(request.UserId, message, null, cancellationToken);
 
@@ -105,7 +105,7 @@ public sealed class ConfirmPaymentRequestCommandHandler(
         )
             return Result.Failure<(PaymentRequest, DateTimeOffset?)>(BillingErrors.RequestNotDecidable);
 
-        if (request.Kind == PaymentRequestKind.RoleChangeTopUp)
+        if (request.Kind == PaymentRequestKind.PlanChangeTopUp)
         {
             request.Confirm(adminId);
             return Result.Success<(PaymentRequest, DateTimeOffset?)>((request, null));