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.Infrastructure/Plans/PlanSeeder.cs

@@ -0,0 +1,24 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using PnvPanel.Application.Common.Interfaces;
+using PnvPanel.Domain.Plans;
+using PnvPanel.Infrastructure.Persistence;
+
+namespace PnvPanel.Infrastructure.Plans;
+
+internal sealed class PlanSeeder(AppDbContext dbContext, ILogger<PlanSeeder> logger) : IPlanSeeder
+{
+    public async Task SeedIfEmptyAsync(CancellationToken cancellationToken)
+    {
+        if (await dbContext.Plans.AnyAsync(cancellationToken))
+            return;
+
+        dbContext.Plans.AddRange(
+            Plan.Create("Стандарт", 3, 0),
+            Plan.Create("Плюс", 6, 1),
+            Plan.Create("Про", 9, 2)
+        );
+        await dbContext.SaveChangesAsync(cancellationToken);
+        logger.LogInformation("Seeded default plans");
+    }
+}