fix(alarmas): decode native failures with the real channel key names

The first pass read 'alarmaId'/'tipo' from the channel payload while the
native side sends 'alarmId'/'type'/'atMillis' (AlarmScheduler.kt:1389).
Every entry would have been dropped silently in production.

The tests passed because the fake was seeded with the same guessed keys,
so they confirmed the mistake instead of catching it. Decoding now goes
through FalloProgramacionNativo.fromMap -- the single place native key
names appear -- and the fixtures build through that same constructor.

test/estado/estado_alarmas_fallos_nativos_test.dart

@@ -1,6 +1,7 @@
 import 'package:flutter_test/flutter_test.dart';
 import 'package:pluriwave/estado/estado_alarmas.dart';
 import 'package:pluriwave/modelos/alarma_musical.dart';
+import 'package:pluriwave/servicios/servicio_alarmas_android.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
 import '../helpers/fakes_alarmas.dart';
@@ -14,6 +15,12 @@ import '../helpers/fakes_alarmas.dart';
 /// The alarm stayed switched on in the list, drawn exactly as if scheduling
 /// had succeeded, and simply never fired — the reported "as if there were no
 /// alarm at all". These tests pin the drain path that makes them visible.
+///
+/// They deliberately build fixtures through [FalloProgramacionNativo.fromMap]
+/// using the REAL native key names (`alarmId`/`type`/`atMillis`, see
+/// `AlarmScheduler.kt:1389-1391`). An earlier draft seeded the fake with
+/// guessed Spanish keys and consumed the same guess, so every entry would
+/// have been silently dropped in production while the tests stayed green.
 void main() {
   TestWidgetsFlutterBinding.ensureInitialized();
 
@@ -27,9 +34,24 @@ void main() {
   EstadoAlarmas crearEstado() =>
       EstadoAlarmas(android: android, iniciarAutomaticamente: false);
 
+  /// Mirrors exactly what the native side puts on the channel.
+  FalloProgramacionNativo falloNativo(String alarmaId, String tipo) =>
+      FalloProgramacionNativo.fromMap({
+        'alarmId': alarmaId,
+        'type': tipo,
+        'atMillis': 1700000000000,
+      });
+
+  test('the fixture helper decodes the real native key names', () {
+    final fallo = falloNativo('a0', ExcepcionAlarma.tipoFalloPreaviso);
+
+    expect(fallo.alarmaId, 'a0');
+    expect(fallo.tipo, ExcepcionAlarma.tipoFalloPreaviso);
+  });
+
   test('a native pre-notice failure becomes a per-alarm exception', () async {
     android.fallosNativos = [
-      {'alarmaId': 'a1', 'tipo': ExcepcionAlarma.tipoFalloPreaviso},
+      falloNativo('a1', ExcepcionAlarma.tipoFalloPreaviso),
     ];
     final estado = crearEstado();
     addTearDown(estado.dispose);
@@ -45,7 +67,7 @@ void main() {
     'a refused foreground-service start becomes a per-alarm exception',
     () async {
       android.fallosNativos = [
-        {'alarmaId': 'a2', 'tipo': ExcepcionAlarma.tipoFalloServicioSonido},
+        falloNativo('a2', ExcepcionAlarma.tipoFalloServicioSonido),
       ];
       final estado = crearEstado();
       addTearDown(estado.dispose);
@@ -61,10 +83,7 @@ void main() {
 
   test('only the alarm whose reschedule failed is marked', () async {
     android.fallosNativos = [
-      {
-        'alarmaId': 'a3',
-        'tipo': ExcepcionAlarma.tipoFalloReprogramacionArranque,
-      },
+      falloNativo('a3', ExcepcionAlarma.tipoFalloReprogramacionArranque),
     ];
     final estado = crearEstado();
     addTearDown(estado.dispose);
@@ -79,19 +98,6 @@ void main() {
     );
   });
 
-  test('malformed native entries are skipped without throwing', () async {
-    android.fallosNativos = [
-      {'tipo': ExcepcionAlarma.tipoFalloPreaviso}, // no alarmaId
-      {'alarmaId': 'a5'}, // no tipo
-    ];
-    final estado = crearEstado();
-    addTearDown(estado.dispose);
-
-    await estado.cargarFallosNativos();
-
-    expect(estado.ultimaExcepcionPara('a5'), isNull);
-  });
-
   test('a failing native read never surfaces as an alarm error', () async {
     // A diagnostics gap must not look like a scheduling problem: an older
     // native build simply has no such channel method.