refactor update backend to host-managed PDC pipeline

scripts/Prepare-PdccOut.ps1

@@ -0,0 +1,59 @@
+param(
+    [Parameter(Mandatory = $true)]
+    [string]$SourceDir,
+
+    [Parameter(Mandatory = $true)]
+    [string]$OutputDir,
+
+    [string]$PlatformKey = "",
+
+    [string[]]$InstallerFiles = @()
+)
+
+$ErrorActionPreference = "Stop"
+
+$SourceDir = [System.IO.Path]::GetFullPath($SourceDir)
+$OutputDir = [System.IO.Path]::GetFullPath($OutputDir)
+
+if (-not (Test-Path -LiteralPath $SourceDir)) {
+    throw "Source directory not found: $SourceDir"
+}
+
+if (Test-Path -LiteralPath $OutputDir) {
+    Remove-Item -LiteralPath $OutputDir -Recurse -Force
+}
+New-Item -ItemType Directory -Path $OutputDir -Force | Out-Null
+
+$payloadRoot = if ([string]::IsNullOrWhiteSpace($PlatformKey)) {
+    $OutputDir
+} else {
+    Join-Path $OutputDir $PlatformKey
+}
+
+New-Item -ItemType Directory -Path $payloadRoot -Force | Out-Null
+Get-ChildItem -LiteralPath $SourceDir -Force | ForEach-Object {
+    Copy-Item -LiteralPath $_.FullName -Destination $payloadRoot -Recurse -Force
+}
+
+if ($InstallerFiles.Count -gt 0) {
+    $installerRoot = Join-Path $OutputDir "installers"
+    if (-not (Test-Path -LiteralPath $installerRoot)) {
+        New-Item -ItemType Directory -Path $installerRoot -Force | Out-Null
+    }
+
+    foreach ($installer in $InstallerFiles) {
+        if ([string]::IsNullOrWhiteSpace($installer)) {
+            continue
+        }
+
+        $installerPath = [System.IO.Path]::GetFullPath($installer)
+        if (-not (Test-Path -LiteralPath $installerPath)) {
+            throw "Installer file not found: $installerPath"
+        }
+
+        $targetPath = Join-Path $installerRoot ([System.IO.Path]::GetFileName($installerPath))
+        Copy-Item -LiteralPath $installerPath -Destination $targetPath -Force
+    }
+}
+
+Write-Host "Prepared PDCC staging directory: $payloadRoot"