feat: 二级页面色彩刷新 + 用药/通知/设备重构 + 后端健康档案/通知管线增强 + 大量测试

## 后端
- 健康档案: 新增手术状态字段 + EF 迁移; HealthArchiveService 新增查询方法
- 健康记录: HealthRecordService 新增批量/统计方法; 契约扩展
- 用药: 新增 MedicationScheduleStatus 枚举; MedicationService 排班逻辑调整
- 通知: EfUserNotificationPipeline 重构; 新增 EfReminderCatchUpService; 通知管线支持更多场景
- 用户: UserService 账号删除逻辑; 新增 local_account_file_cleanup; EfUserRepository 扩展
- AI: medication_agent_handler 微调; prompt_manager 优化; AiConversationService 上下文处理
- Endpoint: doctor/medication/exercise/health/notification/user 等多接口调整
- BackgroundService: health_record_reminder_service 重构, 提醒补漏逻辑
- 测试: 新增 account_deletion/doctor_endpoint/medication_schedule/medication_update/prompt_manager 测试

## 前端
- UI 系统: app_theme 大幅重构; app_colors/app_design_tokens/app_module_visuals 调整; 二级页面色彩刷新
- 主页: home_page 背景渐变 + 消息列表提取 _HomeMessages + 通知检查逻辑; chat_messages_view 全面重构
- 用药: medication_list/edit/checkin 三页重构, 新增 medication_ui_logic 抽取
- 通知: notification_prefs_page 重构, 新增 notification_prefs_logic; notification_center 优化
- 设备: device_management 重构, 新增 device_sync_ui_logic; device_scan 优化
- 趋势图: trend_page 大幅重构
- 登录: login_page 重构
- 个人资料: 新增 profile_edit_page; profile_page 优化
- 运动: 新增 exercise/ 目录 + care_plan_ui_logic
- 其他: remaining_pages/report_pages/health_drawer/admin/doctor 等多页面调整
- 组件: common_widgets/app_empty_state/app_error_state/app_future_view/app_toast/ai_content 优化
- Provider: chat_provider/consultation_provider/data_providers/auth_provider 调整
- AndroidManifest: 移除多余权限
- 测试: 新增 ai_content/care_plan/home_message/login_flow/medication_checkin/medication_ui/notification_prefs/profile_device/secondary_page/swipe_delete 等大量测试

## 文档
- 新增 ui-design-system.md 设计系统文档
- 新增 secondary-page-color-refresh 计划 + specs 目录

backend/src/Health.Application/Users/UserContracts.cs

@@ -16,6 +16,10 @@ public sealed record UserProfileUpdateRequest(
     string? Gender,
     DateOnly? BirthDate);
 
+public sealed record AccountFileReferences(
+    IReadOnlyList<string> FileUrls,
+    IReadOnlyList<string> ConversationMetadataJson);
+
 public interface IUserService
 {
     Task<UserProfileDto?> GetProfileAsync(Guid userId, CancellationToken ct);
@@ -26,6 +30,12 @@ public interface IUserService
 public interface IUserRepository
 {
     Task<User?> GetAsync(Guid userId, CancellationToken ct);
+    Task<AccountFileReferences> GetAccountFileReferencesAsync(Guid userId, CancellationToken ct);
     Task SaveChangesAsync(CancellationToken ct);
     Task DeleteAccountDataAsync(Guid userId, CancellationToken ct);
 }
+
+public interface IAccountFileCleanup
+{
+    Task DeleteAsync(Guid userId, AccountFileReferences references, CancellationToken ct);
+}

backend/src/Health.Application/Users/UserService.cs

@@ -1,8 +1,11 @@
 namespace Health.Application.Users;
 
-public sealed class UserService(IUserRepository users) : IUserService
+public sealed class UserService(
+    IUserRepository users,
+    IAccountFileCleanup fileCleanup) : IUserService
 {
     private readonly IUserRepository _users = users;
+    private readonly IAccountFileCleanup _fileCleanup = fileCleanup;
 
     public async Task<UserProfileDto?> GetProfileAsync(Guid userId, CancellationToken ct)
     {
@@ -30,6 +33,10 @@ public sealed class UserService(IUserRepository users) : IUserService
         return true;
     }
 
-    public Task DeleteAccountAsync(Guid userId, CancellationToken ct) =>
-        _users.DeleteAccountDataAsync(userId, ct);
+    public async Task DeleteAccountAsync(Guid userId, CancellationToken ct)
+    {
+        var references = await _users.GetAccountFileReferencesAsync(userId, ct);
+        await _fileCleanup.DeleteAsync(userId, references, ct);
+        await _users.DeleteAccountDataAsync(userId, ct);
+    }
 }