fix(v0.3.0): audio background + emisoras rotas + errores toast + icono

- ServicioAudio: delega a PluriWaveAudioHandler (audio_service) para
  mantener audio vivo en background. AudioService.init() en main.dart.
  onTaskRemoved() libera player. mediaItem con nombre/artista/artwork.
- ServicioRadio: lastcheckok=1 en todas las peticiones — solo emisoras
  verificadas como funcionales por Radio Browser API.
- EstadoRadio: errorStream (broadcast) para errores de reproducción y
  búsqueda. App.dart suscribe y muestra SnackBar flotante 3s.
  Los errores de carga de lista siguen como banner inline.
- Icono: generado con SDXL (morado, ondas radio blancas, Material You).
  5 densidades Android (48-192px), ic_launcher_round añadido.

lib/app.dart

@@ -27,7 +27,7 @@ class PluriWaveApp extends StatelessWidget {
 
   ThemeData _buildTheme(Brightness brightness) {
     final colorScheme = ColorScheme.fromSeed(
-      seedColor: const Color(0xFF6750A4), // Morado Material You
+      seedColor: const Color(0xFF6750A4),
       brightness: brightness,
     );
     return ThemeData(
@@ -41,6 +41,10 @@ class PluriWaveApp extends StatelessWidget {
         shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12)),
         color: colorScheme.surfaceContainerLow,
       ),
+      snackBarTheme: SnackBarThemeData(
+        behavior: SnackBarBehavior.floating,
+        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(8)),
+      ),
     );
   }
 }
@@ -79,6 +83,22 @@ class _PaginaPrincipalState extends State<_PaginaPrincipal> {
     ),
   ];
 
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+    // Suscribir al stream de errores → SnackBar flotante
+    context.read<EstadoRadio>().errorStream.listen((msg) {
+      if (!mounted) return;
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(
+          content: Text(msg),
+          duration: const Duration(seconds: 3),
+          action: SnackBarAction(label: 'OK', onPressed: () {}),
+        ),
+      );
+    });
+  }
+
   @override
   Widget build(BuildContext context) {
     return Scaffold(
@@ -125,12 +145,15 @@ class _PaginaPrincipalState extends State<_PaginaPrincipal> {
                   stream: estado.timer.tiempoRestanteStream,
                   builder: (ctx, snap) {
                     final t = snap.data ?? Duration.zero;
+                    final h = t.inHours;
                     final m = t.inMinutes.remainder(60).toString().padLeft(2, '0');
                     final s = t.inSeconds.remainder(60).toString().padLeft(2, '0');
                     return Column(
                       children: [
-                        Text('${t.inHours > 0 ? "${t.inHours}h " : ""}${m}m ${s}s',
-                            style: Theme.of(ctx).textTheme.headlineMedium),
+                        Text(
+                          '${h > 0 ? "${h}h " : ""}${m}m ${s}s',
+                          style: Theme.of(ctx).textTheme.headlineMedium,
+                        ),
                         const SizedBox(height: 8),
                         FilledButton.tonal(
                           onPressed: () {
@@ -146,13 +169,15 @@ class _PaginaPrincipalState extends State<_PaginaPrincipal> {
               else
                 Wrap(
                   spacing: 8,
-                  children: [15, 30, 60, 90].map((min) => ActionChip(
-                    label: Text('$min min'),
-                    onPressed: () {
-                      estado.iniciarTimer(min);
-                      Navigator.pop(ctx);
-                    },
-                  )).toList(),
+                  children: [15, 30, 60, 90]
+                      .map((min) => ActionChip(
+                            label: Text('$min min'),
+                            onPressed: () {
+                              estado.iniciarTimer(min);
+                              Navigator.pop(ctx);
+                            },
+                          ))
+                      .toList(),
                 ),
             ],
           ),