feat(tutorial): wire tutorial carousel into the first-launch flow

Insert PantallaTutorialAyuda.mostrarSiProcede between the welcome
screen and the recurring what's-new dialog in
_mostrarFlujoPrimerLanzamiento, so the carousel shows once on every
install -- fresh AND existing installs upgrading to this version --
via its own independent one-time flag, without racing either
surface.

test/widgets/pluri_root_header_test.dart

@@ -12,23 +12,12 @@ import 'package:pluriwave/widgets/pluri_root_header.dart';
 /// sleep-timer action that used to live on `app.dart`'s single global
 /// `AppBar` stays reachable from every tab.
 void main() {
-  // [topInset] simulates `MediaQuery.paddingOf(context).top` (status bar /
-  // camera cutout) — the same technique already used by
-  // `pantalla_alarma_sonando_scaffold_test.dart`'s `MediaQuery` override via
-  // `MaterialApp.builder`.
-  Widget host(Widget child, {double topInset = 0}) {
+  Widget host(Widget child) {
     return MaterialApp(
       theme: PluriWaveTheme.dark(),
       locale: const Locale('en'),
       localizationsDelegates: AppLocalizations.localizationsDelegates,
       supportedLocales: AppLocalizations.supportedLocales,
-      builder:
-          (context, app) => MediaQuery(
-            data: MediaQuery.of(
-              context,
-            ).copyWith(padding: EdgeInsets.only(top: topInset)),
-            child: app!,
-          ),
       home: Scaffold(body: child),
     );
   }
@@ -53,13 +42,7 @@ void main() {
       host(PluriRootHeader(title: 'Settings', onSleepTimer: () {})),
     );
 
-    // Keyed lookup (not `find.byType(Padding).first`): the top-inset fix
-    // wraps this content padding in an outer `Padding(top: topInset)`, so
-    // `.first` would no longer reliably resolve to the content row's own
-    // padding.
-    final padding = tester.widget<Padding>(
-      find.byKey(const ValueKey('pluri-root-header-content')),
-    );
+    final padding = tester.widget<Padding>(find.byType(Padding).first);
     final insets = padding.padding as EdgeInsets;
     expect(insets.left, PluriLayout.titleHorizontal);
     expect(insets.right, PluriLayout.rowHorizontal);
@@ -114,92 +97,4 @@ void main() {
       reason: 'actions render before (to the left of) the bedtime button',
     );
   });
-
-  group('fix top-inset: total height and content position track '
-      'MediaQuery.paddingOf(context).top, instead of always sitting flush '
-      'at y=0 under the status bar', () {
-    // Vertical text centering inside the 56px content row means the
-    // title's own top-left never sits exactly AT the header's top-left
-    // (even at topInset=0) — so these tests compare each inset's title
-    // position against the topInset=0 BASELINE, isolating exactly the
-    // inset's own contribution instead of asserting a brittle absolute
-    // offset.
-    Future<double> tituloTopPara(WidgetTester tester, double topInset) async {
-      await tester.pumpWidget(
-        host(
-          PluriRootHeader(title: 'Settings', onSleepTimer: () {}),
-          topInset: topInset,
-        ),
-      );
-      return tester.getTopLeft(find.text('Settings')).dy;
-    }
-
-    testWidgets(
-      'topInset=0 (e.g. desktop/no cutout): total height stays the plain '
-      '56px content height',
-      (tester) async {
-        await tester.pumpWidget(
-          host(PluriRootHeader(title: 'Settings', onSleepTimer: () {})),
-        );
-
-        expect(tester.getSize(find.byType(PluriRootHeader)).height, 56);
-      },
-    );
-
-    testWidgets(
-      'topInset=24 (typical status bar): total height becomes 56+24=80, '
-      'and the title shifts down by exactly the inset relative to the '
-      'topInset=0 baseline',
-      (tester) async {
-        final base = await tituloTopPara(tester, 0);
-        final conInset = await tituloTopPara(tester, 24);
-
-        expect(tester.getSize(find.byType(PluriRootHeader)).height, 80);
-        expect(conInset - base, 24);
-      },
-    );
-
-    testWidgets(
-      'topInset=44 (taller status bar): total height becomes 56+44=100, '
-      'and the title still shifts down by exactly the inset — never '
-      'clipped',
-      (tester) async {
-        final base = await tituloTopPara(tester, 0);
-        final conInset = await tituloTopPara(tester, 44);
-
-        expect(tester.getSize(find.byType(PluriRootHeader)).height, 100);
-        expect(conInset - base, 44);
-      },
-    );
-
-    testWidgets(
-      'topInset=60 (notch/camera-cutout simulation): total height becomes '
-      '56+60=116, and the title still fully clears the inset — never '
-      'overlapping it',
-      (tester) async {
-        final base = await tituloTopPara(tester, 0);
-        final conInset = await tituloTopPara(tester, 60);
-
-        expect(tester.getSize(find.byType(PluriRootHeader)).height, 116);
-        expect(conInset - base, 60);
-      },
-    );
-
-    testWidgets(
-      'PluriRootHeader.height stays the CONTENT height (56) regardless of '
-      'inset — callers doing total-height math must separately add '
-      'MediaQuery.paddingOf(context).top',
-      (tester) async {
-        await tester.pumpWidget(
-          host(
-            PluriRootHeader(title: 'Settings', onSleepTimer: () {}),
-            topInset: 44,
-          ),
-        );
-
-        expect(PluriRootHeader.height, 56);
-        expect(tester.getSize(find.byType(PluriRootHeader)).height, 100);
-      },
-    );
-  });
 }