Refactor GetOrCreateCommand and add AutoMapper profile

Refactored the `GetOrCreateCommand` to simplify the creation
of `Endpoint` entities by delegating the creation logic to
`repo.CreateAsync`.

Added a new `MappingProfile` class using AutoMapper to define
mappings between command objects (`CreateEndpointCommand` and
`GetOrCreateCommand`) and the `Endpoint` entity, improving
code maintainability and reducing boilerplate.

Included necessary `using` directives in `MappingProfile.cs`
to support the new mapping functionality.

src/ReC.Application/Endpoints/MappingProfile.cs

@@ -0,0 +1,18 @@
+using AutoMapper;
+using ReC.Application.Endpoints.Commands;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace ReC.Application.Endpoints;
+
+public class MappingProfile : Profile
+{
+    public MappingProfile()
+    {
+        CreateMap<CreateEndpointCommand, Endpoint>();
+        CreateMap<GetOrCreateCommand, Endpoint>();
+    }
+}