feat: 完成云同步、语音控制与多平台扩展基础架构搭建

本次提交完成了项目核心基础架构升级：
1. 新增动态API中间件与权限控制系统，支持匿名/鉴权接口分离
2. 搭建云同步服务体系，包含认证、任务同步、安全策略等核心模块
3. 实现语音控制全链路，从STT/意图解析到命令执行
4. 新增任务类型、附件实体与相关仓储接口
5. 重构前端配置与代理规则，统一后端端口为5057
6. 新增多平台测试项目与CI脚本优化
7. 完善项目文档与代码注释规范

移除了旧版迁移文件与冗余代理配置，调整项目结构适配跨平台部署需求。

test/Hua.Todo.Maui.Tests/CloudSync/CloudSyncProxyMiddlewareTests.cs

@@ -0,0 +1,94 @@
+using System.Net;
+using System.Net.Http.Json;
+using Hua.Todo.HttpApi.AspNetCore.CloudSync.Services;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.Extensions.DependencyInjection;
+using Xunit;
+
+namespace Hua.Todo.Maui.Tests.CloudSync;
+
+/// <summary>
+/// CloudSyncProxyMiddleware 行为集成测试（MAUI 端）。
+/// 验证云同步路径代理转发、无 URL 时返回 503。
+/// </summary>
+public class CloudSyncProxyMiddlewareTests : IDisposable
+{
+    private readonly WebApplication _app;
+    private readonly HttpClient _client;
+
+    public CloudSyncProxyMiddlewareTests()
+    {
+        var builder = WebApplication.CreateBuilder();
+        builder.WebHost.UseUrls("http://127.0.0.1:0");
+        builder.Services.AddCloudSyncProxy();
+
+        var app = builder.Build();
+
+        app.UseCloudSyncProxy();
+
+        _app = app;
+        _app.StartAsync().GetAwaiter().GetResult();
+
+        _client = new HttpClient { BaseAddress = new Uri(_app.Urls.First()) };
+    }
+
+    [Fact]
+    public async Task Probe_NoCloudSyncUrl_Returns503()
+    {
+        var response = await _client.PostAsJsonAsync("/api/cloud-sync/probe",
+            new { targetUrl = "http://localhost:5173" });
+
+        Assert.Equal(HttpStatusCode.ServiceUnavailable, response.StatusCode);
+        var content = await response.Content.ReadAsStringAsync();
+        Assert.Contains("cloud sync server URL not configured", content);
+    }
+
+    [Fact]
+    public async Task AuthLogin_NoCloudSyncUrl_Returns503()
+    {
+        var response = await _client.PostAsJsonAsync("/api/auth/login",
+            new { username = "admin", password = "123456" });
+
+        Assert.Equal(HttpStatusCode.ServiceUnavailable, response.StatusCode);
+    }
+
+    [Fact]
+    public async Task Tasks_NoCloudSyncUrl_Returns503()
+    {
+        var response = await _client.GetAsync("/api/tasks/");
+
+        Assert.Equal(HttpStatusCode.ServiceUnavailable, response.StatusCode);
+    }
+
+    [Fact]
+    public async Task Tasks_WithoutTrailingSlash_NoCloudSyncUrl_Returns503()
+    {
+        var response = await _client.PostAsJsonAsync("/api/tasks", new { });
+
+        Assert.Equal(HttpStatusCode.ServiceUnavailable, response.StatusCode);
+    }
+
+    [Fact]
+    public async Task SecurityPolicy_NoCloudSyncUrl_Returns503()
+    {
+        var response = await _client.GetAsync("/api/security/policy");
+
+        Assert.Equal(HttpStatusCode.ServiceUnavailable, response.StatusCode);
+    }
+
+    [Fact]
+    public async Task Sync_NoCloudSyncUrl_Returns503()
+    {
+        var response = await _client.PostAsJsonAsync("/api/sync/", new { });
+
+        Assert.Equal(HttpStatusCode.ServiceUnavailable, response.StatusCode);
+    }
+
+    public void Dispose()
+    {
+        _client.Dispose();
+        _app.StopAsync().GetAwaiter().GetResult();
+        _app.DisposeAsync().GetAwaiter().GetResult();
+    }
+}