feat(flutter): 首页频道叠加轮播并改下划线选中

test/home/k28_a_navigation_test.dart

@@ -8,7 +8,6 @@ import 'package:fruitshorts/core/data/models/watch_progress.dart';
 import 'package:fruitshorts/core/data/repositories/favorite_repository.dart';
 import 'package:fruitshorts/core/data/repositories/playback_repository.dart';
 import 'package:fruitshorts/core/data/repositories/watch_history_repository.dart';
-import 'package:fruitshorts/core/theme/app_colors.dart';
 import 'package:fruitshorts/pages/player/player_view.dart';
 import 'package:shared_preferences_platform_interface/in_memory_shared_preferences_async.dart';
 import 'package:shared_preferences_platform_interface/shared_preferences_async_platform_interface.dart';
@@ -49,27 +48,55 @@ void main() {
     expect(find.text('Coming soon'), findsOneWidget);
   });
 
-  testWidgets('should_switch_home_channel_when_chip_is_tapped', (tester) async {
+  testWidgets('should_switch_home_channel_when_underline_tab_is_tapped', (
+    tester,
+  ) async {
     await _pumpApp(tester);
 
-    expect(_chip(tester, 'home-channel-hot').selected, isTrue);
-    expect(_chip(tester, 'home-channel-free').selected, isFalse);
-    expect(_chip(tester, 'home-channel-hot').selectedColor, AppColors.blue);
-    expect(_chip(tester, 'home-channel-free').backgroundColor, AppColors.card);
-    expect(
-      _chip(tester, 'home-channel-free').labelStyle?.color,
-      AppColors.onSurface,
-    );
+    // 悬浮在轮播图上：选中白色下划线，未选中透明占位。
+    expect(_underlineColor(tester, 'hot'), Colors.white);
+    expect(_underlineColor(tester, 'free'), Colors.transparent);
+    expect(_labelStyle(tester, 'hot').fontWeight, FontWeight.w800);
+    expect(_labelStyle(tester, 'free').fontWeight, FontWeight.w600);
+    expect(_labelStyle(tester, 'hot').color, Colors.white);
+    expect(_labelStyle(tester, 'free').color, Colors.white70);
 
     await tester.tap(find.byKey(const Key('home-channel-free')));
     await tester.pumpAndSettle();
 
-    expect(_chip(tester, 'home-channel-hot').selected, isFalse);
-    expect(_chip(tester, 'home-channel-free').selected, isTrue);
-    expect(
-      _chip(tester, 'home-channel-free').labelStyle?.color,
-      AppColors.onPrimary,
+    expect(_underlineColor(tester, 'hot'), Colors.transparent);
+    expect(_underlineColor(tester, 'free'), Colors.white);
+    expect(_labelStyle(tester, 'free').fontWeight, FontWeight.w800);
+  });
+
+  testWidgets('should_render_flush_hero_with_channels_overlaid', (
+    tester,
+  ) async {
+    await _pumpApp(tester);
+
+    final hero = tester.getRect(find.byKey(const Key('home-hero-banner')));
+    expect(hero.width, 390);
+    expect(hero.left, 0);
+    final card = tester.widget<ClipRRect>(
+      find
+          .descendant(
+            of: find.byKey(const Key('home-hero-banner')),
+            matching: find.byType(ClipRRect),
+          )
+          .first,
     );
+    expect(card.borderRadius, BorderRadius.zero);
+
+    // 频道行在 hero Stack 内、位于轮播顶部 8 的位置上。
+    expect(
+      find.ancestor(
+        of: find.byKey(const Key('home-channels')),
+        matching: find.byKey(const Key('home-hero-section')),
+      ),
+      findsOneWidget,
+    );
+    final channels = tester.getRect(find.byKey(const Key('home-channels')));
+    expect(channels.top, closeTo(hero.top + 8, 1));
   });
 
   testWidgets('should_open_theater_search_when_home_search_is_tapped', (
@@ -209,8 +236,22 @@ const _tabKeys = [
   Key('tab-mine'),
 ];
 
-ChoiceChip _chip(WidgetTester tester, String key) =>
-    tester.widget<ChoiceChip>(find.byKey(Key(key)));
+Color? _underlineColor(WidgetTester tester, String name) {
+  final underline = tester.widget<Container>(
+    find.byKey(Key('home-channel-underline-$name')),
+  );
+  return (underline.decoration! as BoxDecoration).color;
+}
+
+TextStyle _labelStyle(WidgetTester tester, String name) {
+  final label = tester.widget<Text>(
+    find.descendant(
+      of: find.byKey(Key('home-channel-$name')),
+      matching: find.byType(Text),
+    ),
+  );
+  return label.style!;
+}
 
 Future<void> _pumpApp(
   WidgetTester tester, {