ci: keep WSL agent online for pipelines [CI]

ci/start-wsl-runner.ps1

@@ -0,0 +1,20 @@
+param(
+    [string]$Distribution = 'Debian',
+    [string]$LinuxUser = 'justme'
+)
+$ErrorActionPreference = 'Stop'
+# systemd services alone do not keep a WSL distribution running.
+# Run a foreground Linux process in a hidden Windows task at user logon.
+if ($Distribution -notmatch '^[a-zA-Z0-9_.-]+$' -or $LinuxUser -notmatch '^[a-zA-Z0-9_.-]+$') {
+    throw 'Distribution and user names must contain only letters, digits, _, . or -.'
+}
+$userName = [Security.Principal.WindowsIdentity]::GetCurrent().Name
+$taskName = "MoShiro WSL runner ($Distribution)"
+$command = "& '$env:SystemRoot\System32\wsl.exe' --distribution $Distribution --user $LinuxUser --exec /bin/sleep infinity"
+$action = New-ScheduledTaskAction -Execute "$env:SystemRoot\System32\WindowsPowerShell\v1.0\powershell.exe" -Argument "-NoProfile -WindowStyle Hidden -Command `"$command`""
+$trigger = New-ScheduledTaskTrigger -AtLogOn -User $userName
+$principal = New-ScheduledTaskPrincipal -UserId $userName -LogonType Interactive -RunLevel Limited
+$settings = New-ScheduledTaskSettingsSet -Hidden -ExecutionTimeLimit ([TimeSpan]::Zero) -MultipleInstances IgnoreNew -AllowStartIfOnBatteries -DontStopIfGoingOnBatteries
+Register-ScheduledTask -TaskName $taskName -Action $action -Trigger $trigger -Principal $principal -Settings $settings -Description 'Keep Debian WSL running for the systemd Woodpecker CI agent.' -Force | Out-Null
+Start-ScheduledTask -TaskName $taskName
+Get-ScheduledTask -TaskName $taskName | Select-Object TaskName, State