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/tests/Health.Tests/medication_update_tests.cs

@@ -0,0 +1,54 @@
+using Health.Application.Medications;
+using Health.Domain.Entities;
+
+namespace Health.Tests;
+
+public sealed class MedicationUpdateTests
+{
+    [Fact]
+    public async Task Update_CanClearAnExistingEndDate()
+    {
+        var medication = new Medication
+        {
+            Id = Guid.NewGuid(),
+            UserId = Guid.NewGuid(),
+            Name = "阿司匹林",
+            StartDate = new DateOnly(2026, 7, 1),
+            EndDate = new DateOnly(2026, 7, 31),
+        };
+        var repository = new FakeMedicationRepository(medication);
+        var service = new MedicationService(repository);
+
+        var updated = await service.UpdateAsync(
+            medication.UserId,
+            medication.Id,
+            new MedicationPatchRequest(
+                null, null, null, null, null, null, null,
+                ClearEndDate: true),
+            CancellationToken.None);
+
+        Assert.True(updated);
+        Assert.Null(medication.EndDate);
+        Assert.True(repository.Saved);
+    }
+
+    private sealed class FakeMedicationRepository(Medication medication) : IMedicationRepository
+    {
+        public bool Saved { get; private set; }
+
+        public Task<IReadOnlyList<Medication>> ListAsync(Guid userId, string? filter, CancellationToken ct) => Task.FromResult<IReadOnlyList<Medication>>([medication]);
+        public Task<IReadOnlyList<Medication>> ListActiveForRemindersAsync(Guid userId, DateOnly today, CancellationToken ct) => Task.FromResult<IReadOnlyList<Medication>>([medication]);
+        public Task<IReadOnlyList<MedicationLog>> ListLogsInWindowAsync(Guid userId, DateTime startUtc, DateTime endUtc, CancellationToken ct) => Task.FromResult<IReadOnlyList<MedicationLog>>([]);
+        public Task<Medication?> GetOwnedAsync(Guid userId, Guid medicationId, CancellationToken ct) => Task.FromResult<Medication?>(medication.UserId == userId && medication.Id == medicationId ? medication : null);
+        public Task<bool> ExistsOwnedAsync(Guid userId, Guid medicationId, CancellationToken ct) => Task.FromResult(medication.UserId == userId && medication.Id == medicationId);
+        public Task<MedicationLog?> GetTodayTakenLogAsync(Guid userId, Guid medicationId, DateTime startUtc, DateTime endUtc, CancellationToken ct) => Task.FromResult<MedicationLog?>(null);
+        public Task<bool> DoseLogExistsAsync(Guid userId, Guid medicationId, TimeOnly scheduledTime, DateTime startUtc, DateTime endUtc, CancellationToken ct) => Task.FromResult(false);
+        public Task<MedicationLog?> GetDoseLogAsync(Guid userId, Guid medicationId, TimeOnly scheduledTime, DateTime startUtc, DateTime endUtc, CancellationToken ct) => Task.FromResult<MedicationLog?>(null);
+        public Task<IReadOnlyList<Medication>> ListActiveForReminderScanAsync(CancellationToken ct) => Task.FromResult<IReadOnlyList<Medication>>([medication]);
+        public Task AddMedicationAsync(Medication value, CancellationToken ct) => Task.CompletedTask;
+        public Task AddLogAsync(MedicationLog log, CancellationToken ct) => Task.CompletedTask;
+        public void DeleteMedication(Medication value) { }
+        public void DeleteLog(MedicationLog log) { }
+        public Task SaveChangesAsync(CancellationToken ct) { Saved = true; return Task.CompletedTask; }
+    }
+}