feat(audit): enchufar audit en handlers de Rol (UDT-010 B8)

4 command handlers del módulo Roles + Permisos ahora auditan:

| Handler                              | Action                 |
|--------------------------------------|------------------------|
| CreateRolCommandHandler              | rol.create             |
| UpdateRolCommandHandler              | rol.update             |
| DeactivateRolCommandHandler          | rol.deactivate         |
| AssignPermisosToRolCommandHandler    | rol.permisos_update    |

Mismo patrón que B7 (using block + post-commit reads outside scope).

Metadata:
- rol.create: after={Codigo, Nombre, Descripcion}
- rol.update: {before, after} diff
- rol.permisos_update: {before, after} con arrays de codigos ordenados

AssignPermisosToRolCommandHandler captura 'before' leyendo
GetByRolCodigoAsync antes del TransactionScope para poder emitir el diff.

4 test classes actualizados con mock de IAuditLogger.

Suite: 378/378 Application.Tests + 141/141 Api.Tests = 519/519 passing.

Refs: sdd/udt-010-auditoria-trazabilidad/{spec#REQ-RM-AUD, design, tasks#B8}

src/api/SIGCM2.Application/Roles/Create/CreateRolCommandHandler.cs

@@ -1,5 +1,7 @@
+using System.Transactions;
 using SIGCM2.Application.Abstractions;
 using SIGCM2.Application.Abstractions.Persistence;
+using SIGCM2.Application.Audit;
 using SIGCM2.Application.Roles.Dtos;
 using SIGCM2.Domain.Entities;
 using SIGCM2.Domain.Exceptions;
@@ -9,10 +11,12 @@ namespace SIGCM2.Application.Roles.Create;
 public sealed class CreateRolCommandHandler : ICommandHandler<CreateRolCommand, RolCreatedDto>
 {
     private readonly IRolRepository _repository;
+    private readonly IAuditLogger _audit;
 
-    public CreateRolCommandHandler(IRolRepository repository)
+    public CreateRolCommandHandler(IRolRepository repository, IAuditLogger audit)
     {
         _repository = repository;
+        _audit = audit;
     }
 
     public async Task<RolCreatedDto> Handle(CreateRolCommand command)
@@ -24,7 +28,23 @@ public sealed class CreateRolCommandHandler : ICommandHandler<CreateRolCommand,
             throw new RolAlreadyExistsException(command.Codigo);
 
         var rol = Rol.ForCreation(command.Codigo, command.Nombre, command.Descripcion);
-        var newId = await _repository.AddAsync(rol);
+
+        int newId;
+        using (var tx = new TransactionScope(
+            TransactionScopeOption.Required,
+            new TransactionOptions { IsolationLevel = IsolationLevel.ReadCommitted },
+            TransactionScopeAsyncFlowOption.Enabled))
+        {
+            newId = await _repository.AddAsync(rol);
+
+            await _audit.LogAsync(
+                action: "rol.create",
+                targetType: "Rol",
+                targetId: newId.ToString(),
+                metadata: new { after = new { rol.Codigo, rol.Nombre, rol.Descripcion } });
+
+            tx.Complete();
+        }
 
         return new RolCreatedDto(
             Id: newId,