refactor(WebUI): configure HtpClient

EnvelopeGenerator.WebUI/EnvelopeGenerator.WebUI/Program.cs

@@ -11,6 +11,13 @@ builder.Services.AddRazorComponents()
     .AddInteractiveServerComponents()
     .AddInteractiveWebAssemblyComponents();
 
+// HttpClient for server-side components (e.g., MainLayout with FontLoader)
+builder.Services.AddScoped<HttpClient>(sp => {
+    var httpClientFactory = sp.GetRequiredService<IHttpClientFactory>();
+    return httpClientFactory.CreateClient();
+});
+builder.Services.AddHttpClient();
+
 // YARP Reverse Proxy
 builder.Services.AddReverseProxy()
     .LoadFromConfig(builder.Configuration.GetSection("ReverseProxy"));