feat:增加统计图表模块

lib/layout/main_screen.dart

@@ -1,6 +1,7 @@
 import 'package:flisp_app/layout/app_drawer.dart';
 import 'package:flisp_app/pages/calendar_page.dart';
 import 'package:flisp_app/pages/flisp_page.dart';
+import 'package:flisp_app/pages/stats_page.dart';
 import 'package:flisp_app/pages/todo_page.dart';
 import 'package:flisp_app/provider/app_provider.dart';
 import 'package:flutter/material.dart';
@@ -25,6 +26,7 @@ class _MainScreenState extends State<MainScreen> {
       icon: Icon(Icons.calendar_month_rounded),
       label: '日程',
     ),
+    BottomNavigationBarItem(icon: Icon(Icons.insert_chart), label: '统计'),
   ];
 
   @override
@@ -89,7 +91,9 @@ class _MainScreenState extends State<MainScreen> {
     }
   }
 
-  Widget _buildFloatingButton(BuildContext context, int index) {
+  Widget? _buildFloatingButton(BuildContext context, int index) {
+    if (index == 3) return null;
+
     return FloatingActionButton(
       onPressed: () => _onPressFloatingButton(index),
       backgroundColor: Colors.transparent,
@@ -115,6 +119,8 @@ class _MainScreenState extends State<MainScreen> {
         return TodoPage(key: _todoPageKey);
       case 2:
         return CalendarPage(key: _calendarPageKey);
+      case 3:
+        return StatsPage();
       default:
         return FlispPage(key: _flispPageKey);
     }