docs/fix(web): título del selector Copiar de y notas de la prueba contra SAP

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

apps/web/src/app/features/documents/document-form.page.ts

@@ -165,6 +165,7 @@ export class DocumentFormPage {
   protected readonly copyFromItems = computed<MenuItem[]>(() =>
     copySources(this.screen.path).map((p) => ({ id: p, label: menuLabel(p), disabled: !this.isNew() })),
   );
+  protected readonly copyListTitle = computed(() => menuLabel(this.copyListFor() ?? ''));
   protected readonly copyListScreen = computed(() => DOCUMENT_SCREENS.find((s) => s.path === this.copyListFor()));
   /** Documentos abiertos del origen elegido, del mismo socio si ya se indicó. */
   protected readonly copyListFilter = computed(() => {