feat: 用药打卡全面重构 - 按次追踪 + 独立打卡页 + 任务区汇总

- 后端用药提醒改为按次粒度(每个服药时间独立判断)
- 新增 per-dose 打卡/取消打卡 API
- 新增 MedicationCheckInPage 独立打卡页(每药每时间单独toggle)
- 用药列表删底部弹窗(编辑/停药),点药品直接进该药打卡页
- 任务区用药汇总为一行(过期待服已服)
- 支持隔天(EveryOtherDay)/每周频率判断
- 删历史对话功能(ConversationItem + conversationListProvider + UI)

health_app/lib/app.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:flutter_localizations/flutter_localizations.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'core/app_router.dart';
 import 'core/app_theme.dart';
@@ -14,6 +15,16 @@ class HealthApp extends ConsumerWidget {
       title: '健康管家',
       debugShowCheckedModeBanner: false,
       theme: AppTheme.lightTheme,
+      localizationsDelegates: const [
+        GlobalMaterialLocalizations.delegate,
+        GlobalWidgetsLocalizations.delegate,
+        GlobalCupertinoLocalizations.delegate,
+      ],
+      supportedLocales: const [
+        Locale('zh', 'CN'),
+        Locale('zh'),
+      ],
+      locale: const Locale('zh'),
       home: const _RootNavigator(),
     );
   }