feat(eq): name Bluetooth devices from the system pairing list

A Bluetooth device only reports its own name through
AudioDeviceInfo.productName while it is enumerated as an active output, i.e.
while it is connected. Paired-but-switched-off devices therefore had no name
to fall back on, and the platform-name cache is in-memory only by design
(bt-device-identity ADR-4), so it self-heals per session ONLY for whatever
happens to be connected. Every other device showed its raw id.

Android already knows those names: BluetoothAdapter.getBondedDevices() lists
every pairing with its name and MAC, connected or not, and nothing in this
app was asking. Read it and seed the platform-name cache from it, keyed
bt_a2dp:<uppercase MAC> to match the ids the audio layer emits.

Seeded BEFORE the active-device query so a live enumeration name, being the
fresher of the two, still wins; a user's custom name outranks both. Re-read
on refrescarDispositivoActual so pairing or renaming a device in system
settings shows up as soon as the list becomes visible.

Reading the bond list is gated by BLUETOOTH_CONNECT from API 31 and by the
legacy BLUETOOTH permission below it, so declare the latter with
maxSdkVersion 30. It is a normal permission: granted at install, no runtime
prompt, no new friction. When the answer is unavailable — permission denied,
no adapter, Bluetooth off — both layers return an empty map rather than
throwing, and the row degrades to the id exactly as before.

Does not help rows persisted under a bt_a2dp:name: placeholder id: those
never had a MAC to match against.

test/estado/estado_ecualizador_test.dart

@@ -1543,6 +1543,93 @@ void main() {
   // builtin_speaker id collision + device removal
   // ---------------------------------------------------------------------------
 
+  group('EstadoEcualizador — bonded Bluetooth names', () {
+    const deviceId = 'bt_a2dp:AA:BB:CC:DD:EE:FF';
+
+    test('a paired but disconnected device resolves its system name', () async {
+      final fakeDispositivo = FakeServicioDispositivoAudio(
+        nombresEmparejados: {'AA:BB:CC:DD:EE:FF': 'Omoda'},
+      );
+      final eq = EstadoEcualizador(
+        audio: FakeServicioAudio(),
+        servicio: FakeServicioEcualizador(
+          eqMultiDeviceEnabled: true,
+          presetsDispositivo: {deviceId: PresetEcualizador.rock},
+        ),
+        dispositivoAudio: fakeDispositivo,
+        emisoraActualUuid: () => null,
+      );
+
+      await eq.cargarPersistido();
+
+      // The device was never seen on the stream this session, so the only
+      // possible source is the system's bonded-device list.
+      expect(eq.nombrePlataforma(deviceId), equals('Omoda'));
+      eq.dispose();
+    });
+
+    test('a live enumeration name wins over the bonded one', () async {
+      final fakeDispositivo = FakeServicioDispositivoAudio(
+        nombresEmparejados: {'AA:BB:CC:DD:EE:FF': 'Stale pairing name'},
+      );
+      final eq = EstadoEcualizador(
+        audio: FakeServicioAudio(),
+        servicio: FakeServicioEcualizador(eqMultiDeviceEnabled: true),
+        dispositivoAudio: fakeDispositivo,
+        emisoraActualUuid: () => null,
+      );
+      await eq.cargarPersistido();
+
+      fakeDispositivo.emitirDispositivo(
+        const DispositivoAudio(
+          id: deviceId,
+          tipo: TipoDispositivo.bluetoothA2dp,
+          nombre: 'Omoda',
+        ),
+      );
+      await Future<void>.delayed(Duration.zero);
+
+      expect(eq.nombrePlataforma(deviceId), equals('Omoda'));
+      eq.dispose();
+    });
+
+    test('a custom name still beats the bonded one', () async {
+      final fakeDispositivo = FakeServicioDispositivoAudio(
+        nombresEmparejados: {'AA:BB:CC:DD:EE:FF': 'OMODA 5'},
+      );
+      final eq = EstadoEcualizador(
+        audio: FakeServicioAudio(),
+        servicio: FakeServicioEcualizador(
+          eqMultiDeviceEnabled: true,
+          nombresDispositivos: {deviceId: 'Coche'},
+        ),
+        dispositivoAudio: fakeDispositivo,
+        emisoraActualUuid: () => null,
+      );
+      await eq.cargarPersistido();
+
+      expect(
+        eq.nombreVisible(deviceId, eq.nombrePlataforma(deviceId)),
+        equals('Coche'),
+      );
+      eq.dispose();
+    });
+
+    test('a failing bonded-name lookup never breaks startup', () async {
+      final eq = EstadoEcualizador(
+        audio: FakeServicioAudio(),
+        servicio: FakeServicioEcualizador(eqMultiDeviceEnabled: true),
+        dispositivoAudio: FakeServicioDispositivoAudioThrows(),
+        emisoraActualUuid: () => null,
+      );
+
+      await eq.cargarPersistido();
+
+      expect(eq.nombrePlataforma('bt_a2dp:AA:BB'), isEmpty);
+      eq.dispose();
+    });
+  });
+
   group('EstadoEcualizador — builtin_speaker collision guard', () {
     test(
       'an unknown-type device reported under the base id creates no entry',