enhance: test on Windows and fix what it found (#1348)

Adds a weekly and on-demand workflow that runs the cross-compiled tests on Windows Server 2025 Core in a [dockur/windows](https://github.com/dockur/windows) QEMU VM, and fixes the Windows bugs it found in host and UNC paths, env handling, shell quoting, post-task scripts, health checks, checkout, action symlinks, step summaries, Git client certificates and docker mode from a Windows host.

Host-mode steps now emit UTF-8, `bash` falls back to Git's bash instead of the WSL launcher, the runner can run as a native Windows service, steps can keep background helpers with `RUNNER_TRACKING_ID`, and Windows arm64 binaries are released.

Fixes: https://gitea.com/gitea/runner/issues/1339
Fixes: https://gitea.com/gitea/runner/issues/637
Fixes: https://gitea.com/gitea/runner/issues/1172
Fixes: https://gitea.com/gitea/runner/issues/347
Reviewed-on: https://gitea.com/gitea/runner/pulls/1348
Reviewed-by: bircni <[email protected]>

scripts/test-windows.ps1

@@ -0,0 +1,31 @@
+$ErrorActionPreference = 'Stop'
+$ProgressPreference = 'SilentlyContinue'
+$results = '\\host.lan\Data'
+$root = $PSScriptRoot
+try {
+    New-Item -ItemType Directory "$root\logs" | Out-Null
+    $env:Path = "C:\git\cmd;C:\git\bin;C:\pwsh;C:\node;$env:Path"
+    git config --global --add safe.directory C:/OEM/src # setup copied it as SYSTEM, the tests run as the logged-on user
+
+    $failed = 0
+    Write-Output "==> Running $((Get-Content "$root\tests.txt").Count) test binaries on $([Environment]::ProcessorCount) cores"
+    Get-Content "$root\tests.txt" | ForEach-Object -ThrottleLimit ([Environment]::ProcessorCount) -Parallel {
+        $binary, $package = $_ -split ' ', 2
+        $started = Get-Date
+        Set-Location "$using:root\src\$package"
+        cmd.exe /d /c "$using:root\bin\$binary -test.v -test.timeout=60m -test.parallel=8 > $using:root\logs\$($package -replace '/', '-').log 2>&1"
+        [pscustomobject]@{ Package = $package; ExitCode = $LASTEXITCODE; Seconds = [int]((Get-Date) - $started).TotalSeconds }
+    } | ForEach-Object {
+        $line = "ok $($_.Package) $($_.Seconds)s"
+        if ($_.ExitCode -ne 0) {
+            $line = "FAIL $($_.Package) $($_.Seconds)s exit $($_.ExitCode)"
+            $failed = 1
+        }
+        Add-Content "$results\summary.txt" $line
+    }
+    Copy-Item "$root\logs\*" $results
+} catch {
+    $_ | Out-String | Tee-Object "$results\error.txt"
+    $failed = 1
+}
+Set-Content "$results\exitcode" $failed