refactor(envelope): consolidate draft flow into upsert command

- extend CreateEnvelopeCommand to support draft updates and send intent

- merge draft save logic into CreateEnvelopeCommandHandler and remove duplicate handler

- add DocReceiverElement writer abstraction and infrastructure registration for SQL-based field upserts

EnvelopeGenerator.Infrastructure/DependencyInjection.cs

@@ -12,9 +12,11 @@ using DigitalData.UserManager.Domain.Entities;
 using CommandDotNet.Execution;
 using EnvelopeGenerator.Infrastructure.Repositories;
 using EnvelopeGenerator.Infrastructure.Executor;
+using EnvelopeGenerator.Infrastructure.Writers;
 using EnvelopeGenerator.Application.Common.Interfaces.Repositories;
 using EnvelopeGenerator.Application.Common.Interfaces.SQLExecutor;
 using EnvelopeGenerator.Application.Common.Interfaces.Services;
+using EnvelopeGenerator.Application.Common.Interfaces;
 using DigitalData.EmailProfilerDispatcher.Abstraction.Entities;
 #elif NETFRAMEWORK
 using System;
@@ -56,6 +58,7 @@ namespace EnvelopeGenerator.Infrastructure
             services.TryAddScoped<IEnvelopeTypeRepository, EnvelopeTypeRepository>();
             services.TryAddScoped<IReceiverRepository, ReceiverRepository>();
             services.TryAddScoped<IEnvelopeReceiverReadOnlyRepository, EnvelopeReceiverReadOnlyRepository>();
+            services.TryAddScoped<IDocReceiverElementWriter, DocReceiverElementWriter>();
 
             // User Preferences — distributed cache (dbo.TBDD_CACHE)
             services.TryAddScoped<IUserPreferencesService, UserPreferencesService>();
@@ -214,4 +217,4 @@ namespace EnvelopeGenerator.Infrastructure
 #endif
         }
     }
-}
+}