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/tests/PnvPanel.Domain.Tests/Plans/PlanTests.cs

@@ -0,0 +1,31 @@
+using PnvPanel.Domain.Plans;
+using Xunit;
+
+namespace PnvPanel.Domain.Tests.Plans;
+
+public class PlanTests
+{
+    [Fact]
+    public void Create_SetsFieldsAndEnablesByDefault()
+    {
+        var plan = Plan.Create("Стандарт", 3, 0);
+
+        Assert.Equal("Стандарт", plan.Name);
+        Assert.Equal(3, plan.ConfigCount);
+        Assert.Equal(0, plan.SortOrder);
+        Assert.True(plan.IsEnabled);
+    }
+
+    [Fact]
+    public void Update_ChangesFieldsIncludingIsEnabled()
+    {
+        var plan = Plan.Create("Стандарт", 3, 0);
+
+        plan.Update("Плюс", 6, 1, false);
+
+        Assert.Equal("Плюс", plan.Name);
+        Assert.Equal(6, plan.ConfigCount);
+        Assert.Equal(1, plan.SortOrder);
+        Assert.False(plan.IsEnabled);
+    }
+}