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.Api/Endpoints/AdminPlanEndpoints.cs

@@ -0,0 +1,69 @@
+using PnvPanel.Api.Common;
+using PnvPanel.Application.Admin.Plans;
+using PnvPanel.Application.Common.Messaging;
+using PnvPanel.Infrastructure.Identity;
+
+namespace PnvPanel.Api.Endpoints;
+
+public static class AdminPlanEndpoints
+{
+    public static IEndpointRouteBuilder MapAdminPlanEndpoints(this IEndpointRouteBuilder app)
+    {
+        var admin = app.MapGroup("/api/admin/plans")
+            .WithTags("Admin.Plans")
+            .RequireAuthorization(policy => policy.RequireRole(RoleNames.Admin));
+
+        admin.MapGet("", ListPlans).Produces<IReadOnlyList<AdminPlanDto>>();
+        admin.MapPost("", CreatePlan).Produces<AdminPlanDto>();
+        admin.MapPut("/{id:guid}", UpdatePlan).Produces<AdminPlanDto>();
+        admin.MapDelete("/{id:guid}", DeletePlan).Produces(StatusCodes.Status204NoContent);
+
+        return app;
+    }
+
+    private static async Task<IResult> ListPlans(ISender sender, CancellationToken cancellationToken)
+    {
+        var result = await sender.Send(new ListAdminPlansQuery(), cancellationToken);
+        return result.ToHttpResult();
+    }
+
+    private static async Task<IResult> CreatePlan(
+        CreatePlanCommand command,
+        ISender sender,
+        CancellationToken cancellationToken
+    )
+    {
+        var result = await sender.Send(command, cancellationToken);
+        return result.ToHttpResult();
+    }
+
+    private static async Task<IResult> UpdatePlan(
+        Guid id,
+        UpdatePlanBody body,
+        ISender sender,
+        CancellationToken cancellationToken
+    )
+    {
+        var command = new UpdatePlanCommand(
+            id,
+            body.Name,
+            body.ConfigCount,
+            body.SortOrder,
+            body.IsEnabled
+        );
+        var result = await sender.Send(command, cancellationToken);
+        return result.ToHttpResult();
+    }
+
+    private static async Task<IResult> DeletePlan(
+        Guid id,
+        ISender sender,
+        CancellationToken cancellationToken
+    )
+    {
+        var result = await sender.Send(new DeletePlanCommand(id), cancellationToken);
+        return result.ToHttpResult();
+    }
+}
+
+public sealed record UpdatePlanBody(string Name, int ConfigCount, int SortOrder, bool IsEnabled);