feat: 二维码访问功能，统一端点管道增强，端点迁移至 Services 层

- 新增二维码生成端点，自动检测局域网 IP，前端扫一扫即可打开网站
  - 提取 IApiResponse 接口，ServiceRequestBinder 支持强类型请求 DTO 绑定
  - FileStream 端点迁移至 AppEndpoints 统一注册，管道支持 FileStreamResponse 原始文件返回
  - 文件库端点全面使用 MapGet<TService, TRequest> 泛型注册
  - 移除 Avalonia-API/Extensions 中的业务端点文件，统一由 Services 层管理

Avalonia-API/Configuration/ServicesConfiguration.cs

@@ -6,6 +6,7 @@ using Avalonia_Services.Endpoints;
 using Avalonia_Services.Services;
 using Avalonia_Services.Services.AuthService;
 using Avalonia_Services.Services.FileLibrary;
+using Avalonia_Services.Services.QrCode;
 using Microsoft.AspNetCore.DataProtection;
 using Microsoft.AspNetCore.Authentication.JwtBearer;
 using Microsoft.IdentityModel.Tokens;
@@ -41,6 +42,8 @@ namespace Avalonia_API.Configuration
             services.AddScoped<WeatherForecastService>();
             services.AddScoped<IFileLibraryService, FileLibraryService>();
             services.AddScoped<IFileLibraryEndpointService, FileLibraryEndpointService>();
+            services.AddScoped<IFileStreamService, FileStreamService>();
+            services.AddScoped<IQrCodeService, QrCodeService>();
             services.AddHostedService<FileLibraryScanHostedService>();
             services.AddDataProtection()
                 .PersistKeysToFileSystem(new DirectoryInfo(Path.Combine(AppContext.BaseDirectory, "data-protection-keys")));