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-Services/Extensions/DesktopEndpointAdapter.cs

@@ -109,10 +109,19 @@ namespace Avalonia_Services.Extensions
             Dictionary<string, string>? query = null)
         {
             // 查找匹配的端点（忽略大小写 + 方法匹配）
-            var endpoint = _endpoints.Endpoints.FirstOrDefault(e =>
-                e.SupportsHost(EndpointHostTarget.Pc) &&
-                string.Equals(e.Pattern, path, StringComparison.OrdinalIgnoreCase) &&
-                string.Equals(e.HttpMethod, method, StringComparison.OrdinalIgnoreCase));
+            var match = _endpoints.Endpoints
+                .Where(e =>
+                    e.SupportsHost(EndpointHostTarget.Pc) &&
+                    string.Equals(e.HttpMethod, method, StringComparison.OrdinalIgnoreCase))
+                .Select(e => new
+                {
+                    Endpoint = e,
+                    IsMatched = ServiceEndpointPatternMatcher.TryMatch(e.Pattern, path, out var routeValues),
+                    RouteValues = routeValues,
+                })
+                .FirstOrDefault(candidate => candidate.IsMatched);
+
+            var endpoint = match?.Endpoint;
 
             if (endpoint is null)
             {
@@ -127,6 +136,7 @@ namespace Avalonia_Services.Extensions
                 Body = body,
                 Headers = headers ?? new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase),
                 Query = query ?? new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase),
+                RouteValues = match!.RouteValues,
                 Items = { ["ServiceProvider"] = _serviceProvider },
             };