feat(ui): refine navigation and sleep timer

lib/pantallas/pantalla_buscar.dart

@@ -5,6 +5,7 @@ import 'package:provider/provider.dart';
 import '../estado/estado_radio.dart';
 import '../widgets/pluri_glass_surface.dart';
 import '../widgets/pluri_icon.dart';
+import '../widgets/pluri_layout.dart';
 import '../widgets/pluri_premium_widgets.dart';
 import 'package:pluriwave/widgets/tarjeta_emisora.dart';
 
@@ -68,7 +69,7 @@ class _PantallaBuscarState extends State<PantallaBuscar> {
     final theme = Theme.of(context);
 
     return ListView(
-      padding: const EdgeInsets.fromLTRB(0, 0, 0, 124),
+      padding: PluriLayout.pageListPadding,
       children: [
         PluriScreenHeader(
           title: 'Buscar senal',
@@ -80,7 +81,7 @@ class _PantallaBuscarState extends State<PantallaBuscar> {
           ),
         ),
         Padding(
-          padding: const EdgeInsets.fromLTRB(16, 10, 16, 0),
+          padding: const EdgeInsets.fromLTRB(PluriLayout.horizontal, 10, PluriLayout.horizontal, 0),
           child: PluriGlassSurface(
             padding: const EdgeInsets.all(10),
             borderRadius: BorderRadius.circular(999),
@@ -135,7 +136,7 @@ class _PantallaBuscarState extends State<PantallaBuscar> {
     final theme = Theme.of(context);
     final pais = estado.paisCercanoDetectado;
     return Padding(
-      padding: const EdgeInsets.fromLTRB(16, 8, 16, 0),
+      padding: const EdgeInsets.fromLTRB(PluriLayout.horizontal, 8, PluriLayout.horizontal, 0),
       child: PluriGlassSurface(
         padding: const EdgeInsets.all(12),
         child: Column(
@@ -209,7 +210,7 @@ class _PantallaBuscarState extends State<PantallaBuscar> {
   ) {
     final theme = Theme.of(context);
     return Padding(
-      padding: const EdgeInsets.fromLTRB(16, 8, 16, 0),
+      padding: const EdgeInsets.fromLTRB(PluriLayout.horizontal, 8, PluriLayout.horizontal, 0),
       child: PluriGlassSurface(
         padding: const EdgeInsets.all(10),
         child: Column(
@@ -277,7 +278,7 @@ class _PantallaBuscarState extends State<PantallaBuscar> {
     return ListView.separated(
       shrinkWrap: true,
       physics: const NeverScrollableScrollPhysics(),
-      padding: const EdgeInsets.fromLTRB(16, 16, 16, 16),
+      padding: const EdgeInsets.all(PluriLayout.horizontal),
       itemCount: total,
       separatorBuilder: (_, __) => const SizedBox(height: 10),
       itemBuilder: (context, i) {