feat: módulo Finanzas (plan de cuentas y asientos contables con cancelación)

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

apps/web/src/app/features/masters/master-field.ts

@@ -108,8 +108,8 @@ export class MasterField {
   });
   protected readonly ro = computed(() => {
     const f = this.field();
-    if (f.type === 'text') return f.readonly || (f.immutable && this.saved());
-    return 'readonly' in f ? f.readonly : false;
+    if ('immutable' in f && f.immutable && this.saved()) return true;
+    return 'readonly' in f ? !!f.readonly : false;
   });
   protected readonly lookup = computed(() => {
     const f = this.field();