ci: trace Windows build IO one-off

.github/scripts/windows-io-trace.ps1

@@ -0,0 +1,41 @@
+param(
+    [Parameter(Mandatory = $true)]
+    [ValidateSet("mark", "transition", "stop")]
+    [string]$Action,
+
+    [string]$Label,
+
+    [string]$From,
+
+    [string]$To
+)
+
+$ErrorActionPreference = "Stop"
+
+function Invoke-Wpr {
+    param([string[]]$Arguments)
+
+    & wpr @Arguments
+    if ($LASTEXITCODE -ne 0) {
+        throw "wpr $($Arguments -join ' ') failed with exit code $LASTEXITCODE"
+    }
+}
+
+switch ($Action) {
+    "mark" {
+        Invoke-Wpr @("-marker", $Label)
+    }
+    "transition" {
+        Invoke-Wpr @("-marker", "step:end:$From")
+        Invoke-Wpr @("-marker", "step:start:$To")
+    }
+    "stop" {
+        Invoke-Wpr @("-marker", "step:end:$Label")
+
+        $traceRoot = Join-Path $env:RUNNER_TEMP "codex-io-trace"
+        New-Item -ItemType Directory -Force -Path $traceRoot | Out-Null
+        $tracePath = Join-Path $traceRoot "windows-io-$($env:GITHUB_JOB)-$($env:GITHUB_RUN_ID)-$($env:GITHUB_RUN_ATTEMPT).etl"
+        Invoke-Wpr @("-stop", $tracePath)
+        Write-Output "saved Windows I/O trace to $tracePath"
+    }
+}