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/Support/TicketAuthorization.cs

@@ -4,8 +4,8 @@ namespace PnvPanel.Application.Support;
 
 internal static class TicketAuthorization
 {
-    // Совпадает со значением Infrastructure.Identity.RoleNames.Admin — см. пояснение в
-    // CreateRoleRequestTicketCommandHandler (Application не может ссылаться на Infrastructure).
+    // Совпадает со значением Infrastructure.Identity.RoleNames.Admin (Application не может
+    // ссылаться на Infrastructure).
     private const string AdminRoleName = "admin";
 
     public static bool IsAdmin(CurrentUserProfile? profile) =>