Add README and batch build scripts

Program.cs

@@ -360,10 +360,11 @@ class Program
 
     static string BuildUpstreamProxyAuthHeader()
     {
-        if (string.IsNullOrWhiteSpace(UPSTREAM_USER) || string.IsNullOrWhiteSpace(UPSTREAM_PASS))
+        if (string.IsNullOrWhiteSpace(UPSTREAM_USER))
             return string.Empty;
 
-        string encoded = Convert.ToBase64String(Encoding.ASCII.GetBytes($"{UPSTREAM_USER}:{UPSTREAM_PASS}"));
+        string pass = UPSTREAM_PASS ?? string.Empty;
+        string encoded = Convert.ToBase64String(Encoding.ASCII.GetBytes($"{UPSTREAM_USER}:{pass}"));
         return $"Proxy-Authorization: Basic {encoded}\r\n";
     }
 }

README.md

@@ -13,7 +13,7 @@
 ## Требования
 
 - Windows 10/11 или Windows Server
-- .NET SDK 6.0+ (для сборки)
+- .NET SDK 5.0+ (для сборки)
 - Доступ к корпоративному proxy (например `proxy.syktsu.ru:3128`)
 
 Важно: проект использует WinHTTP API (`winhttp.dll`), поэтому запуск только на Windows.

anti-syktsu-proxy.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>net6.0</TargetFramework>
+    <TargetFramework>net5.0</TargetFramework>
     <Nullable>disable</Nullable>
     <ImplicitUsings>disable</ImplicitUsings>
     <AssemblyName>anti-syktsu-proxy</AssemblyName>

run.bat

@@ -10,7 +10,7 @@ if not exist "%EXE%" (
 )
 
 set "UPSTREAM_PROXY=proxy.syktsu.ru:3128"
-set "UPSTREAM_USER=%USERDOMAIN%\%USERNAME%"
+set "UPSTREAM_USER=%USERNAME%"
 set "UPSTREAM_PASS="
 
 echo [run] UPSTREAM_PROXY=%UPSTREAM_PROXY%