Add PowerShell script for Xi Xu API configuration

This script prompts for an API key, creates a configuration file, and sets environment variables for the Xi Xu AI Inference model provider.

codex.ps1

@@ -0,0 +1,68 @@
+param(
+    [string]$ApiKey
+)
+
+if ([string]::IsNullOrWhiteSpace($ApiKey)) {
+    $secure = Read-Host "请输入 XIXU_API_KEY" -AsSecureString
+    $ptr = [Runtime.InteropServices.Marshal]::SecureStringToBSTR($secure)
+    try {
+        $ApiKey = [Runtime.InteropServices.Marshal]::PtrToStringAuto($ptr)
+    }
+    finally {
+        [Runtime.InteropServices.Marshal]::ZeroFreeBSTR($ptr)
+    }
+}
+
+$ConfigDir = Join-Path $HOME ".codex"
+$ConfigFile = Join-Path $ConfigDir "config.toml"
+
+New-Item -ItemType Directory -Force -Path $ConfigDir | Out-Null
+if (-not (Test-Path $ConfigFile)) {
+    New-Item -ItemType File -Force -Path $ConfigFile | Out-Null
+}
+
+$content = Get-Content $ConfigFile -Raw -ErrorAction SilentlyContinue
+if ($null -eq $content) {
+    $content = ""
+}
+
+if ($content -match '(?m)^[ \t]*model_provider[ \t]*=') {
+    $content = [regex]::Replace(
+        $content,
+        '(?m)^[ \t]*model_provider[ \t]*=.*$',
+        'model_provider = "xixu"'
+    )
+} else {
+    if ($content.Length -gt 0 -and -not $content.EndsWith("`n")) {
+        $content += "`r`n"
+    }
+    $content += 'model_provider = "xixu"' + "`r`n"
+}
+
+$content = [regex]::Replace(
+    $content,
+    '(?ms)^\[model_providers\.xixu\]\s*.*?(?=^\[|\z)',
+    ''
+)
+
+$xixuBlock = @'
+
+[model_providers.xixu]
+name = "Xi Xu''s AI Inference"
+base_url = "https://api.xi-xu.me/v1"
+env_key = "XIXU_API_KEY"
+'@
+
+$content = $content.TrimEnd() + "`r`n" + $xixuBlock + "`r`n"
+
+Set-Content -Path $ConfigFile -Value $content -Encoding UTF8
+
+$env:XIXU_API_KEY = $ApiKey
+[System.Environment]::SetEnvironmentVariable("XIXU_API_KEY", $ApiKey, "User")
+
+Write-Host "已完成："
+Write-Host "1. 更新 $ConfigFile"
+Write-Host "2. 设置当前会话环境变量 XIXU_API_KEY"
+Write-Host "3. 持久化为用户级环境变量"
+Write-Host ""
+Write-Host '重新打开 PowerShell 后会自动生效。当前会话已可直接使用。'