feat(udt-011): T400.30 — inject TimeProvider into Infrastructure critical services

AuditLogger, SecurityEventLogger: inject TimeProvider and use
_timeProvider.GetUtcNow().UtcDateTime for occurredAt timestamps.
JwtService: inject TimeProvider; use GetUtcNow() for token IssuedAt/Expires.
DI: update JwtService factory to pass sp.GetRequiredService<TimeProvider>().
Repositories: remove ?? DateTime.UtcNow fallback in UpdateAsync since callers
always provide FechaModificacion via domain mutators.

src/api/SIGCM2.Infrastructure/Persistence/MedioRepository.cs

@@ -85,7 +85,7 @@ public sealed class MedioRepository : IMedioRepository
             Tipo = (int)m.Tipo,
             m.PlataformaEmpresaId,
             m.Activo,
-            FechaModificacion = m.FechaModificacion ?? DateTime.UtcNow,
+            FechaModificacion = m.FechaModificacion,
             m.Id,
         });
     }