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-PC/Authentication/PcAuthEndpointService.cs

@@ -3,7 +3,6 @@ using Avalonia_Common.Core;
 using Avalonia_Services.Core;
 using Avalonia_Services.Services.AuthService;
 using System;
-using System.Text.Json;
 using System.Threading.Tasks;
 
 namespace Avalonia_PC.Authentication
@@ -14,16 +13,10 @@ namespace Avalonia_PC.Authentication
     /// </summary>
     public sealed class PcAuthEndpointService(PcGlobalTokenService tokenService) : IPcAuthEndpointService
     {
-        private static readonly JsonSerializerOptions JsonOptions = new()
-        {
-            PropertyNameCaseInsensitive = true,
-        };
-
         /// <inheritdoc />
-        public async Task<object?> AuthorizeAsync(ServiceEndpointContext ctx)
+        public async Task<IApiResponse> AuthorizeAsync(PcAuthorizeRequest request, ServiceEndpointContext ctx)
         {
-            var request = Deserialize<PcAuthorizeRequest>(ctx.Body);
-            var token = await tokenService.AuthorizeAsync(request?.AuthorizationCode);
+            var token = await tokenService.AuthorizeAsync(request.AuthorizationCode);
             if (token is null)
             {
                 ctx.StatusCode = 401;
@@ -34,10 +27,9 @@ namespace Avalonia_PC.Authentication
         }
 
         /// <inheritdoc />
-        public async Task<object?> RefreshAsync(ServiceEndpointContext ctx)
+        public async Task<IApiResponse> RefreshAsync(PcRefreshRequest request, ServiceEndpointContext ctx)
         {
-            var request = Deserialize<PcRefreshRequest>(ctx.Body);
-            var token = request?.Token ?? ExtractBearerToken(ctx.GetHeader("Authorization"));
+            var token = request.Token ?? ExtractBearerToken(ctx.GetHeader("Authorization"));
             var refreshed = await tokenService.RefreshAsync(token);
             if (refreshed is null)
             {
@@ -49,25 +41,11 @@ namespace Avalonia_PC.Authentication
         }
 
         /// <inheritdoc />
-        public Task<object?> LogoutAsync(ServiceEndpointContext ctx)
+        public Task<IApiResponse> LogoutAsync(PcLogoutRequest request, ServiceEndpointContext ctx)
         {
-            var request = Deserialize<PcLogoutRequest>(ctx.Body);
-            var token = request?.Token ?? ExtractBearerToken(ctx.GetHeader("Authorization"));
+            var token = request.Token ?? ExtractBearerToken(ctx.GetHeader("Authorization"));
             tokenService.Logout(token);
-            return Task.FromResult<object?>(ResponseHelper.Succeed("退出成功"));
-        }
-
-        /// <summary>
-        /// 将 JSON 请求体反序列化为指定类型。
-        /// </summary>
-        /// <typeparam name="T">目标类型。</typeparam>
-        /// <param name="body">JSON 请求体字符串，可为空。</param>
-        /// <returns>反序列化后的对象；若 body 为空则返回默认值。</returns>
-        private static T? Deserialize<T>(string? body)
-        {
-            return string.IsNullOrWhiteSpace(body)
-                ? default
-                : JsonSerializer.Deserialize<T>(body, JsonOptions);
+            return Task.FromResult<IApiResponse>(ResponseHelper.Succeed("退出成功"));
         }
 
         /// <summary>