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/Billing/CreatePaymentRequest/CreatePaymentRequestCommandHandler.cs

@@ -33,7 +33,7 @@ public sealed class CreatePaymentRequestCommandHandler(
         if (!profile.BillingEnabled)
             return Result.Failure<PaymentRequestDto>(BillingErrors.NotEnabled);
 
-        if (profile.MaxConfigs == RoleQuota.Unlimited)
+        if (profile.ConfigQuota == RoleQuota.Unlimited)
             return Result.Failure<PaymentRequestDto>(BillingErrors.UnlimitedRoleNotSupported);
 
         var pricing = await dbContext.PricingSettings.AsNoTracking().FirstOrDefaultAsync(cancellationToken);
@@ -54,16 +54,16 @@ public sealed class CreatePaymentRequestCommandHandler(
             .PricingDiscountTiers.AsNoTracking()
             .Where(t => t.PricingSettingsId == pricing.Id)
             .ToListAsync(cancellationToken);
-        var discountPercent = PricingDiscount.ResolvePercent(discountTiers, profile.MaxConfigs);
+        var discountPercent = PricingDiscount.ResolvePercent(discountTiers, profile.ConfigQuota);
 
-        var amount = PricingDiscount.Apply(rate * profile.MaxConfigs * command.Period.ToMonths(), discountPercent);
+        var amount = PricingDiscount.Apply(rate * profile.ConfigQuota * command.Period.ToMonths(), discountPercent);
 
         var claimed = await AdvisoryLock.RunAsync(
             dbContext,
             userId,
             async lockedCancellationToken =>
             {
-                // RoleChangeTopUp не считается активной подписной заявкой — доплата за смену роли не
+                // PlanChangeTopUp не считается активной подписной заявкой — доплата за смену тарифа не
                 // должна мешать пользователю продлить/оформить обычную подписку.
                 var hasActiveRequest = await dbContext.PaymentRequests.AnyAsync(
                     r =>