Refactor entity selection to use EntityType enum

Replaced string-based entity identifiers in CRUD procedure and command classes with a strongly-typed EntityType enum. Updated all relevant handlers and records to use the new enum property, improving type safety and maintainability. Added necessary using directives and updated documentation comments to reflect these changes.

src/ReC.Application/Endpoints/Commands/UpdateEndpointCommand.cs

@@ -1,6 +1,7 @@
 using MediatR;
 using ReC.Application.Common.Procedures.UpdateProcedure;
 using ReC.Application.Common.Procedures.UpdateProcedure.Dto;
+using ReC.Application.Common.Procedures;
 
 namespace ReC.Application.Endpoints.Commands;
 
@@ -17,7 +18,7 @@ public class UpdateEndpointProcedureHandler(ISender sender) : IRequestHandler<Up
     {
         return await sender.Send(new UpdateObjectProcedure
         {
-            Entity = "ENDPOINT",
+            Entity = EntityType.Endpoint,
             Id = request.Id,
             Endpoint = request.Data
         }, cancel);