feat(favorites): manage favorite groups in ui

lib/pantallas/pantalla_ajustes.dart

@@ -13,6 +13,7 @@ import '../estado/estado_idioma.dart';
 import '../estado/estado_radio.dart';
 import '../l10n/gen/app_localizations.dart';
 import '../modelos/emisora.dart';
+import '../modelos/grupo_favoritos.dart';
 import '../widgets/ecualizador_widget.dart';
 import '../widgets/pluri_glass_surface.dart';
 import '../widgets/pluri_icon.dart';
@@ -64,6 +65,8 @@ class _AjustesContent extends StatelessWidget {
         SizedBox(height: 12),
         _SeccionOrdenListas(),
         SizedBox(height: 12),
+        _SeccionGruposFavoritos(),
+        SizedBox(height: 12),
         _SeccionEmisoraPreferida(),
         SizedBox(height: 12),
         _SeccionEmisoras(),
@@ -693,6 +696,141 @@ class _SeccionOrdenListas extends StatelessWidget {
   }
 }
 
+class _SeccionGruposFavoritos extends StatelessWidget {
+  const _SeccionGruposFavoritos();
+
+  Future<void> _editarGrupo(BuildContext context, [GrupoFavoritos? grupo]) async {
+    final l10n = AppLocalizations.of(context);
+    final controller = TextEditingController(text: grupo?.nombre ?? '');
+    final nombre = await showModalBottomSheet<String>(
+      context: context,
+      isScrollControlled: true,
+      showDragHandle: true,
+      builder: (ctx) {
+        final bottom = MediaQuery.viewInsetsOf(ctx).bottom;
+        return Padding(
+          padding: EdgeInsets.fromLTRB(20, 0, 20, bottom + 24),
+          child: Column(
+            mainAxisSize: MainAxisSize.min,
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: [
+              Text(
+                grupo == null ? l10n.favoriteGroupsAdd : l10n.favoriteGroupsEdit,
+                style: Theme.of(ctx).textTheme.titleLarge,
+              ),
+              const SizedBox(height: 16),
+              TextField(
+                controller: controller,
+                autofocus: true,
+                maxLength: 28,
+                decoration: InputDecoration(
+                  labelText: l10n.favoriteGroupsNameLabel,
+                  helperText: l10n.favoriteGroupsNameTooLong,
+                  border: const OutlineInputBorder(),
+                ),
+              ),
+              const SizedBox(height: 12),
+              FilledButton.icon(
+                icon: const Icon(Icons.save_rounded),
+                label: Text(AppLocalizations.of(ctx).saveQuickAccessButton),
+                onPressed: () {
+                  final value = controller.text.trim();
+                  if (value.isEmpty || value.length > 28) return;
+                  Navigator.pop(ctx, value);
+                },
+              ),
+            ],
+          ),
+        );
+      },
+    );
+    controller.dispose();
+    if (nombre == null || !context.mounted) return;
+    final estado = context.read<EstadoRadio>();
+    if (grupo == null) {
+      await estado.crearGrupoFavoritos(nombre);
+    } else {
+      await estado.renombrarGrupoFavoritos(grupo.id, nombre);
+    }
+    if (!context.mounted) return;
+    ScaffoldMessenger.of(context).showSnackBar(
+      SnackBar(content: Text(grupo == null ? l10n.favoriteGroupsCreated : l10n.favoriteGroupsUpdated)),
+    );
+  }
+
+  Future<void> _eliminarGrupo(BuildContext context, GrupoFavoritos grupo) async {
+    final l10n = AppLocalizations.of(context);
+    await context.read<EstadoRadio>().eliminarGrupoFavoritos(grupo.id);
+    if (!context.mounted) return;
+    ScaffoldMessenger.of(context).showSnackBar(
+      SnackBar(content: Text(l10n.favoriteGroupsDeleted)),
+    );
+  }
+
+  String _nombreVisible(AppLocalizations l10n, GrupoFavoritos grupo) =>
+      grupo.esSinAsignar ? l10n.favoriteGroupsUnassigned : grupo.nombre;
+
+  @override
+  Widget build(BuildContext context) {
+    final estado = context.watch<EstadoRadio>();
+    final l10n = AppLocalizations.of(context);
+    final grupos = estado.gruposFavoritos;
+    return PluriGlassSurface(
+      child: Column(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          Row(
+            children: [
+              const Icon(Icons.playlist_add_check_circle_rounded),
+              const SizedBox(width: 12),
+              Expanded(
+                child: Text(
+                  l10n.favoriteGroupsTitle,
+                  style: Theme.of(context).textTheme.titleMedium,
+                ),
+              ),
+              TextButton.icon(
+                icon: const Icon(Icons.add_rounded),
+                label: Text(l10n.favoriteGroupsAdd),
+                onPressed: () => _editarGrupo(context),
+              ),
+            ],
+          ),
+          const SizedBox(height: 4),
+          Text(l10n.favoriteGroupsDescription),
+          const SizedBox(height: 8),
+          for (final grupo in grupos)
+            ListTile(
+              contentPadding: EdgeInsets.zero,
+              leading: Icon(
+                grupo.esSinAsignar ? Icons.lock_rounded : Icons.folder_rounded,
+              ),
+              title: Text(_nombreVisible(l10n, grupo)),
+              subtitle: grupo.esSinAsignar ? Text(l10n.favoriteGroupsProtectedHint) : null,
+              trailing: grupo.esSinAsignar
+                  ? null
+                  : Wrap(
+                      spacing: 4,
+                      children: [
+                        IconButton(
+                          tooltip: l10n.favoriteGroupsEdit,
+                          icon: const Icon(Icons.edit_rounded),
+                          onPressed: () => _editarGrupo(context, grupo),
+                        ),
+                        IconButton(
+                          tooltip: l10n.favoriteGroupsDelete,
+                          icon: const Icon(Icons.delete_outline_rounded),
+                          onPressed: () => _eliminarGrupo(context, grupo),
+                        ),
+                      ],
+                    ),
+            ),
+        ],
+      ),
+    );
+  }
+}
+
 class _SeccionEmisoraPreferida extends StatelessWidget {
   const _SeccionEmisoraPreferida();