fix：导航栏交互和UI

lib/features/shell_page.dart

@@ -9,20 +9,40 @@ import '../theme/yanting_text.dart';
 import '../widgets/bottom_tab_bar.dart';
 import '../widgets/mini_player.dart';
 
-class ShellPage extends ConsumerWidget {
+class ShellPage extends ConsumerStatefulWidget {
   const ShellPage({required this.child, required this.currentPath, super.key});
 
   final Widget child;
   final String currentPath;
 
   @override
-  Widget build(BuildContext context, WidgetRef ref) {
+  ConsumerState<ShellPage> createState() => _ShellPageState();
+}
+
+class _ShellPageState extends ConsumerState<ShellPage> {
+  static const double _compactHeaderThreshold = 34;
+
+  bool _showCompactHeader = false;
+
+  @override
+  void didUpdateWidget(covariant ShellPage oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    if (oldWidget.currentPath != widget.currentPath && _showCompactHeader) {
+      _showCompactHeader = false;
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
     final theme = ShadTheme.of(context);
     final player = ref.watch(audioPlayerControllerProvider);
     final controller = ref.read(audioPlayerControllerProvider.notifier);
     final canPop = GoRouter.of(context).canPop();
-    final selectedIndex = _tabs.indexWhere((tab) => tab.path == currentPath);
+    final selectedIndex = _tabs.indexWhere(
+      (tab) => tab.path == widget.currentPath,
+    );
     final safeIndex = selectedIndex < 0 ? 0 : selectedIndex;
+    final header = _headerForPath(widget.currentPath);
 
     return Scaffold(
       backgroundColor: theme.colorScheme.background,
@@ -30,30 +50,45 @@ class ShellPage extends ConsumerWidget {
         backgroundColor: theme.colorScheme.background,
         surfaceTintColor: Colors.transparent,
         elevation: 0,
+        scrolledUnderElevation: 0,
+        centerTitle: true,
         leading: canPop
             ? ShadIconButton.ghost(
                 onPressed: () => context.pop(),
                 icon: const Icon(LucideIcons.chevronLeft, size: 18),
               )
             : null,
-        title: Column(
-          crossAxisAlignment: CrossAxisAlignment.start,
-          children: [
-            Text('研听', style: YantingText.listTitle),
-            Text('全球机构研报中文解读', style: YantingText.meta.copyWith(fontSize: 12)),
-          ],
-        ),
-        bottom: PreferredSize(
-          preferredSize: const Size.fromHeight(1),
-          child: ColoredBox(
-            color: theme.colorScheme.border,
-            child: const SizedBox(height: 1, width: double.infinity),
+        title: AnimatedOpacity(
+          opacity: _showCompactHeader ? 1 : 0,
+          duration: const Duration(milliseconds: 160),
+          curve: Curves.easeOut,
+          child: Column(
+            mainAxisSize: MainAxisSize.min,
+            crossAxisAlignment: CrossAxisAlignment.center,
+            children: [
+              Text(
+                header.title,
+                textAlign: TextAlign.center,
+                style: YantingText.listTitle,
+              ),
+              if (header.subtitle.isNotEmpty)
+                Text(
+                  header.subtitle,
+                  maxLines: 1,
+                  overflow: TextOverflow.ellipsis,
+                  textAlign: TextAlign.center,
+                  style: YantingText.meta.copyWith(fontSize: 12),
+                ),
+            ],
           ),
         ),
       ),
       body: ColoredBox(
         color: theme.colorScheme.background,
-        child: Stack(children: [Positioned.fill(child: child)]),
+        child: NotificationListener<ScrollNotification>(
+          onNotification: _handleScrollNotification,
+          child: Stack(children: [Positioned.fill(child: widget.child)]),
+        ),
       ),
       bottomNavigationBar: SafeArea(
         top: false,
@@ -71,6 +106,34 @@ class ShellPage extends ConsumerWidget {
       ),
     );
   }
+
+  bool _handleScrollNotification(ScrollNotification notification) {
+    if (notification.metrics.axis != Axis.vertical) {
+      return false;
+    }
+    final next = notification.metrics.pixels > _compactHeaderThreshold;
+    if (next != _showCompactHeader && mounted) {
+      setState(() => _showCompactHeader = next);
+    }
+    return false;
+  }
+}
+
+_ShellHeader _headerForPath(String path) {
+  return switch (path) {
+    AppRoutes.reports => const _ShellHeader('研报', '全部已发布研报解读'),
+    AppRoutes.institutions => const _ShellHeader('机构', '可获取研报的机构'),
+    AppRoutes.listen => const _ShellHeader('听单', '已转音频的研报解读'),
+    AppRoutes.profile => const _ShellHeader('我的', ''),
+    _ => const _ShellHeader('研听', '全球机构研报中文解读'),
+  };
+}
+
+class _ShellHeader {
+  const _ShellHeader(this.title, this.subtitle);
+
+  final String title;
+  final String subtitle;
 }
 
 class _TabItem {