feat(ui): refine navigation and sleep timer

lib/pantallas/pantalla_ajustes.dart

@@ -14,6 +14,7 @@ import '../modelos/emisora.dart';
 import '../widgets/ecualizador_widget.dart';
 import '../widgets/pluri_glass_surface.dart';
 import '../widgets/pluri_icon.dart';
+import '../widgets/pluri_layout.dart';
 import '../widgets/pluri_premium_widgets.dart';
 
 class PantallaAjustes extends StatelessWidget {
@@ -22,7 +23,7 @@ class PantallaAjustes extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return ListView(
-      padding: const EdgeInsets.fromLTRB(0, 0, 0, 124),
+      padding: PluriLayout.pageListPadding,
       children: const [
         PluriScreenHeader(
           title: 'Ajustes',
@@ -35,7 +36,7 @@ class PantallaAjustes extends StatelessWidget {
           ),
         ),
         Padding(
-          padding: EdgeInsets.symmetric(horizontal: 16),
+          padding: PluriLayout.pageContentPadding,
           child: _AjustesContent(),
         ),
       ],
@@ -54,6 +55,8 @@ class _AjustesContent extends StatelessWidget {
         SizedBox(height: 12),
         _SeccionGrabaciones(),
         SizedBox(height: 12),
+        _SeccionTimerSueno(),
+        SizedBox(height: 12),
         _SeccionEmisoraPreferida(),
         SizedBox(height: 12),
         _SeccionEmisoras(),
@@ -158,6 +161,177 @@ class _SeccionGrabaciones extends StatelessWidget {
   }
 }
 
+class _SeccionTimerSueno extends StatelessWidget {
+  const _SeccionTimerSueno();
+
+  Future<void> _anadirPreset(BuildContext context) async {
+    final duracion = await showModalBottomSheet<Duration>(
+      context: context,
+      isScrollControlled: true,
+      showDragHandle: true,
+      builder: (_) => const _FormularioDuracionTimer(),
+    );
+    if (duracion == null || !context.mounted) return;
+    await context.read<EstadoRadio>().agregarTimerSuenoPreset(duracion);
+    if (!context.mounted) return;
+    ScaffoldMessenger.of(context).showSnackBar(
+      SnackBar(
+        content: Text(
+          'Acceso rápido añadido: ${_formatearDuracionTimer(duracion)}',
+        ),
+      ),
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final estado = context.watch<EstadoRadio>();
+    final presets = estado.timerSuenoPresetsSegundos;
+    return PluriGlassSurface(
+      child: Column(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          Row(
+            children: [
+              const Icon(Icons.bedtime_rounded),
+              const SizedBox(width: 12),
+              Text(
+                'Timer de sueño',
+                style: Theme.of(context).textTheme.titleMedium,
+              ),
+              const Spacer(),
+              TextButton.icon(
+                icon: const Icon(Icons.add_rounded),
+                label: const Text('Añadir'),
+                onPressed: () => _anadirPreset(context),
+              ),
+            ],
+          ),
+          const SizedBox(height: 8),
+          Text(
+            'Personalizá los accesos rápidos que aparecen al apagar la radio automáticamente.',
+            style: Theme.of(context).textTheme.bodySmall,
+          ),
+          const SizedBox(height: 12),
+          Wrap(
+            spacing: 8,
+            runSpacing: 8,
+            children: [
+              for (final segundos in presets)
+                InputChip(
+                  label: Text(
+                    _formatearDuracionTimer(Duration(seconds: segundos)),
+                  ),
+                  onDeleted:
+                      presets.length <= 1
+                          ? null
+                          : () => context
+                              .read<EstadoRadio>()
+                              .eliminarTimerSuenoPreset(segundos),
+                ),
+            ],
+          ),
+          const SizedBox(height: 8),
+          Align(
+            alignment: Alignment.centerLeft,
+            child: TextButton.icon(
+              icon: const Icon(Icons.restore_rounded),
+              label: const Text('Restaurar tiempos recomendados'),
+              onPressed:
+                  () => context.read<EstadoRadio>().restaurarTimerSuenoPresets(),
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}
+
+class _FormularioDuracionTimer extends StatefulWidget {
+  const _FormularioDuracionTimer();
+
+  @override
+  State<_FormularioDuracionTimer> createState() => _FormularioDuracionTimerState();
+}
+
+class _FormularioDuracionTimerState extends State<_FormularioDuracionTimer> {
+  final _horasCtrl = TextEditingController();
+  final _minutosCtrl = TextEditingController(text: '15');
+  final _segundosCtrl = TextEditingController();
+
+  @override
+  void dispose() {
+    _horasCtrl.dispose();
+    _minutosCtrl.dispose();
+    _segundosCtrl.dispose();
+    super.dispose();
+  }
+
+  int _leer(TextEditingController ctrl) => int.tryParse(ctrl.text.trim()) ?? 0;
+
+  void _guardar() {
+    final duracion = Duration(
+      hours: _leer(_horasCtrl),
+      minutes: _leer(_minutosCtrl),
+      seconds: _leer(_segundosCtrl),
+    );
+    if (duracion <= Duration.zero) {
+      ScaffoldMessenger.of(context).showSnackBar(
+        const SnackBar(content: Text('Elegí una duración mayor que cero.')),
+      );
+      return;
+    }
+    Navigator.pop(context, duracion);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final bottom = MediaQuery.viewInsetsOf(context).bottom;
+    return SafeArea(
+      child: Padding(
+        padding: EdgeInsets.fromLTRB(18, 0, 18, 18 + bottom),
+        child: Column(
+          mainAxisSize: MainAxisSize.min,
+          crossAxisAlignment: CrossAxisAlignment.stretch,
+          children: [
+            Text(
+              'Nuevo acceso rápido',
+              style: Theme.of(context).textTheme.titleLarge,
+            ),
+            const SizedBox(height: 12),
+            Row(
+              children: [
+                Expanded(child: _campo(_horasCtrl, 'Horas')),
+                const SizedBox(width: 8),
+                Expanded(child: _campo(_minutosCtrl, 'Minutos')),
+                const SizedBox(width: 8),
+                Expanded(child: _campo(_segundosCtrl, 'Segundos')),
+              ],
+            ),
+            const SizedBox(height: 16),
+            FilledButton.icon(
+              icon: const Icon(Icons.save_rounded),
+              label: const Text('Guardar acceso rápido'),
+              onPressed: _guardar,
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  Widget _campo(TextEditingController controller, String label) {
+    return TextField(
+      controller: controller,
+      keyboardType: TextInputType.number,
+      decoration: InputDecoration(
+        labelText: label,
+        border: const OutlineInputBorder(),
+      ),
+    );
+  }
+}
+
 class _SeccionEcualizador extends StatelessWidget {
   const _SeccionEcualizador();
 
@@ -463,7 +637,7 @@ class _FormularioEmisoraState extends State<_FormularioEmisora> {
   Widget build(BuildContext context) {
     final bottom = MediaQuery.of(context).viewInsets.bottom;
     return Padding(
-      padding: EdgeInsets.fromLTRB(16, 16, 16, 16 + bottom),
+      padding: EdgeInsets.fromLTRB(PluriLayout.horizontal, PluriLayout.horizontal, PluriLayout.horizontal, PluriLayout.horizontal + bottom),
       child: Form(
         key: _formKey,
         child: Column(
@@ -711,3 +885,16 @@ class _SeccionInfo extends StatelessWidget {
     );
   }
 }
+
+String _formatearDuracionTimer(Duration duracion) {
+  final horas = duracion.inHours;
+  final minutos = duracion.inMinutes.remainder(60);
+  final segundos = duracion.inSeconds.remainder(60);
+  if (horas > 0) {
+    return '${horas}h ${minutos.toString().padLeft(2, '0')}m ${segundos.toString().padLeft(2, '0')}s';
+  }
+  if (minutos > 0) {
+    return segundos == 0 ? '$minutos min' : '${minutos}m ${segundos}s';
+  }
+  return '$segundos s';
+}