修复IIS部署问题：

1. LoggingMiddleware修复：处理已关闭的Stream，防止ObjectDisposedException
2. Startup.cs添加UseStaticFiles中间件：支持静态文件访问

Haoliang.Api/Middleware/LoggingMiddleware.cs

@@ -25,6 +25,7 @@ namespace Haoliang.Api.Middleware
         public async Task Invoke(HttpContext context)
         {
             var originalBodyStream = context.Response.Body;
+            MemoryStream? responseBody = null;
             
             try
             {
@@ -32,8 +33,7 @@ namespace Haoliang.Api.Middleware
                 await LogRequestAsync(context);
 
                 // Capture response
-                using (var responseBody = new MemoryStream())
-                {
+                responseBody = new MemoryStream();
                 context.Response.Body = responseBody;
 
                 await _next(context);
@@ -42,6 +42,8 @@ namespace Haoliang.Api.Middleware
                 await LogResponseAsync(context, responseBody);
 
                 // Copy the response body to the original stream
+                if (context.Response.ContentLength > 0)
+                {
                     responseBody.Seek(0, SeekOrigin.Begin);
                     await responseBody.CopyToAsync(originalBodyStream);
                 }
@@ -51,6 +53,14 @@ namespace Haoliang.Api.Middleware
                 await _loggingService.LogErrorAsync($"Unhandled exception in logging middleware: {ex.Message}", ex);
                 throw;
             }
+            finally
+            {
+                if (responseBody != null)
+                {
+                    await responseBody.DisposeAsync();
+                }
+                context.Response.Body = originalBodyStream;
+            }
         }
 
         private async Task LogRequestAsync(HttpContext context)

Haoliang.Api/Startup.cs

@@ -66,6 +66,7 @@ namespace Haoliang.Api
             }
 
             // 中间件顺序很重要
+            app.UseStaticFiles();
             app.UseMiddleware<LoggingMiddleware>();
             app.UseCors("AllowAll");
             app.UseMiddleware<ExceptionMiddleware>();