新增夜间模式相关代码

lib/pages/battery_health_page.dart

@@ -3,6 +3,7 @@ import 'dart:developer' as dev;
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:device_info_plus/device_info_plus.dart';
+import '../theme/theme_service.dart';
 
 // --- 本地导入 ---
 import '../models/device_matching.dart';
@@ -626,6 +627,56 @@ class _BatteryHealthPageState extends State<BatteryHealthPage> {
     return ChargeUtils.getChargeTypeLabel(_isWireless, _chargeType);
   }
 
+  // 🆕 夜间模式切换弹窗  ← 加在这里
+  void _showThemePicker() {
+    showModalBottomSheet(
+      context: context,
+      builder: (ctx) {
+        final current = ThemeService.notifier.value;
+        return SafeArea(
+          child: Column(
+            mainAxisSize: MainAxisSize.min,
+            children: [
+              ListTile(
+                leading: const Icon(Icons.brightness_auto),
+                title: const Text('跟随系统'),
+                trailing: current == ThemeMode.system
+                    ? const Icon(Icons.check)
+                    : null,
+                onTap: () {
+                  ThemeService.setMode(ThemeMode.system);
+                  Navigator.pop(ctx);
+                },
+              ),
+              ListTile(
+                leading: const Icon(Icons.light_mode),
+                title: const Text('浅色'),
+                trailing: current == ThemeMode.light
+                    ? const Icon(Icons.check)
+                    : null,
+                onTap: () {
+                  ThemeService.setMode(ThemeMode.light);
+                  Navigator.pop(ctx);
+                },
+              ),
+              ListTile(
+                leading: const Icon(Icons.dark_mode),
+                title: const Text('深色'),
+                trailing: current == ThemeMode.dark
+                    ? const Icon(Icons.check)
+                    : null,
+                onTap: () {
+                  ThemeService.setMode(ThemeMode.dark);
+                  Navigator.pop(ctx);
+                },
+              ),
+            ],
+          ),
+        );
+      },
+    );
+  }
+
   // ---------- Build ----------
   @override
   Widget build(BuildContext context) {
@@ -695,7 +746,7 @@ class _BatteryHealthPageState extends State<BatteryHealthPage> {
                     );
                     break;
                   case 'dark_mode':
-                    // 夜间模式切换逻辑（1.7.0 再实现）
+                    _showThemePicker();
                     break;
                 }
               },
@@ -705,11 +756,7 @@ class _BatteryHealthPageState extends State<BatteryHealthPage> {
                   value: 'about', // 🟢 新增
                   child: Text('关于'),
                 ),
-                const PopupMenuItem(
-                  value: 'dark_mode',
-                  enabled: false, // 暂时灰显
-                  child: Text('夜间模式（开发中）'),
-                ),
+                const PopupMenuItem(value: 'dark_mode', child: Text('夜间模式')),
               ],
             ),
           ],