feat: 用药提醒功能 + 移除医生相关页面

- 后端新增 GET /api/medications/reminders 接口
- 前端任务卡片区显示真实用药提醒
- 移除 DoctorListPage/DoctorChatPage 路由
- 移除"找医生"面板按钮
- 医生端另做 Web 页面

health_app/lib/services/health_service.dart

@@ -83,6 +83,12 @@ class MedicationService {
   Future<void> confirm(String id) async {
     await _api.post('/api/medications/$id/confirm');
   }
+
+  Future<List<Map<String, dynamic>>> getReminders() async {
+    final res = await _api.get('/api/medications/reminders');
+    final list = res.data['data'] as List? ?? [];
+    return list.cast<Map<String, dynamic>>();
+  }
 }
 
 /// 饮食服务