Add AutoMapper profile for envelope mapping

Introduces `CreateEnvelopeMappingProfile` class to define
mapping between `Envelope` entity and `CreateEnvelopeResponse`
DTO using AutoMapper's `CreateMap` method.

EnvelopeGenerator.Application/Envelopes/Commands/CreateEnvelopeMappingProfile.cs

@@ -0,0 +1,18 @@
+using AutoMapper;
+using EnvelopeGenerator.Domain.Entities;
+
+namespace EnvelopeGenerator.Application.Envelopes.Commands;
+
+/// <summary>
+/// 
+/// </summary>
+public class CreateEnvelopeMappingProfile : Profile
+{
+    /// <summary>
+    /// 
+    /// </summary>
+    public CreateEnvelopeMappingProfile()
+    {
+        CreateMap<Envelope, CreateEnvelopeResponse>();
+    }
+}