first commit

lib/screens/home_screen.dart

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+import 'package:flutter/material.dart';
+import 'package:flutter/foundation.dart' show kIsWeb;
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'today_screen.dart';
+import 'stats_screen.dart';
+import 'settings_screen.dart';
+import '../providers/background_sync_provider.dart';
+
+class HomeScreen extends ConsumerStatefulWidget {
+  const HomeScreen({super.key});
+
+  @override
+  ConsumerState<HomeScreen> createState() => _HomeScreenState();
+}
+
+class _HomeScreenState extends ConsumerState<HomeScreen> {
+  int _currentIndex = 0;
+
+  final List<Widget> _screens = [
+    const TodayScreen(),
+    const StatsScreen(),
+    const SettingsScreen(),
+  ];
+
+  @override
+  void initState() {
+    super.initState();
+    // Web 平台不启动后台同步服务
+    if (!kIsWeb) {
+      // 启动后台同步服务
+      WidgetsBinding.instance.addPostFrameCallback((_) {
+        final syncService = ref.read(backgroundSyncServiceProvider);
+        syncService.start();
+      });
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      body: IndexedStack(
+        index: _currentIndex,
+        children: _screens,
+      ),
+      bottomNavigationBar: NavigationBar(
+        selectedIndex: _currentIndex,
+        onDestinationSelected: (index) {
+          setState(() {
+            _currentIndex = index;
+          });
+        },
+        destinations: const [
+          NavigationDestination(
+            icon: Icon(Icons.today_outlined),
+            selectedIcon: Icon(Icons.today),
+            label: 'Today',
+          ),
+          NavigationDestination(
+            icon: Icon(Icons.bar_chart_outlined),
+            selectedIcon: Icon(Icons.bar_chart),
+            label: 'Stats',
+          ),
+          NavigationDestination(
+            icon: Icon(Icons.settings_outlined),
+            selectedIcon: Icon(Icons.settings),
+            label: 'Settings',
+          ),
+        ],
+      ),
+    );
+  }
+}
+