feat(buscar): add discovery landing state, filter pills, counter, and sort

test/pantallas/pantalla_inicio_rebuild_test.dart

@@ -89,8 +89,19 @@ void main() {
     expect(registro.any((linea) => linea.contains('PantallaInicio')), isFalse);
 
     // Probe control: a real data change DOES rebuild the screen.
+    //
+    // WU6 correction: this used to be `estado.cargarPopulares()`, which
+    // notifies `emisorasInicio`/`cargandoPopulares` — fields the removed
+    // discovery grid (`_gridEmisoras`) used to read. Task 6.5 relocated
+    // that grid to `PantallaBuscar` and deleted it here, so
+    // `PantallaInicio` no longer selects either field; `cargarPopulares()`
+    // would silently turn this probe into a false negative instead of a
+    // real control. Toggling a favorite is the correct replacement — the
+    // remaining "Tus emisoras" section (`_seccionTusEmisoras`) selects
+    // `listaFavoritos` directly.
     registro.clear();
-    await tester.runAsync(estado.cargarPopulares);
+    final emisoraProbe = emisoraDemo(uuid: 'probe-1', nombre: 'Probe Uno');
+    await tester.runAsync(() => estado.toggleFavorito(emisoraProbe));
     await tester.pump();
     expect(registro.any((linea) => linea.contains('PantallaInicio')), isTrue);
     debugPrintRebuildDirtyWidgets = false;