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.WebApi/Endpoints/medication_endpoints.cs

@@ -77,8 +77,10 @@ public static class MedicationEndpoints
         group.MapDelete("/{id:guid}/confirm-dose/{time}", async (Guid id, string time, HttpContext http, IMedicationService medications, CancellationToken ct) =>
         {
             var userId = GetUserId(http);
-            await medications.CancelDoseAsync(userId, id, TimeOnly.Parse(time), ct);
-            return Results.Ok(new { code = 0, data = new { success = true }, message = (string?)null });
+            var cancelled = await medications.CancelDoseAsync(userId, id, TimeOnly.Parse(time), ct);
+            return cancelled
+                ? Results.Ok(new { code = 0, data = new { success = true }, message = (string?)null })
+                : Results.Ok(new { code = 40004, data = (object?)null, message = "未找到对应的服药打卡记录" });
         });
     }
 
@@ -112,14 +114,19 @@ public static class MedicationEndpoints
         if (root.TryGetProperty("frequency", out var f) && Enum.TryParse<MedicationFrequency>(f.GetString(), out var freq))
             frequency = freq;
 
+        var hasEndDate = root.TryGetProperty("endDate", out var ed);
+        var clearEndDate = hasEndDate &&
+            (ed.ValueKind == JsonValueKind.Null || string.IsNullOrWhiteSpace(ed.GetString()));
+
         return new MedicationPatchRequest(
             root.TryGetProperty("name", out var n) ? n.GetString() : null,
             root.TryGetProperty("dosage", out var dg) ? dg.GetString() : null,
             frequency,
             root.TryGetProperty("timeOfDay", out _) ? ReadTimes(root, "timeOfDay") : null,
             root.TryGetProperty("startDate", out var sd) && DateOnly.TryParse(sd.GetString(), out var startDate) ? startDate : null,
-            root.TryGetProperty("endDate", out var ed) && DateOnly.TryParse(ed.GetString(), out var endDate) ? endDate : null,
-            root.TryGetProperty("notes", out var nt) ? nt.GetString() : null);
+            hasEndDate && !clearEndDate && DateOnly.TryParse(ed.GetString(), out var endDate) ? endDate : null,
+            root.TryGetProperty("notes", out var nt) ? nt.GetString() : null,
+            clearEndDate);
     }
 
     private static List<TimeOnly> ReadTimes(JsonElement root, string propertyName)