feat: 完成v1.3.0架构对齐与Web端根路径托管全量开发

- 重构架构：抽离AddCloudSyncServer到扩展类，补全中间层文档对齐
- 修复根路径404与鉴权跳转：新增中间件处理浏览器请求302跳转
- 实现种子数据初始化：添加默认管理员账号自动创建逻辑
- 优化前端代理与构建：新增Vite代理配置与自动构建Target
- 补全测试与文档：新增集成测试，更新开发与部署文档

test/Hua.Todo.Host.Tests/CloudSync/CloudSyncAuthSecurityPolicyTests.cs

@@ -6,7 +6,7 @@ using Hua.Todo.Application.Common;
 using Hua.Todo.Application.Repositories;
 using Hua.Todo.Application.Services.CloudSync.Models;
 using Hua.Todo.Core.Entities;
-using Hua.Todo.HttpApi.AspNetCore.CloudSync.Services;
+using Hua.Todo.HttpApi.AspNetCore.CloudSync;
 using Hua.Todo.HttpApi.AspNetCore.DynamicApi;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Hosting;