Machine number input at PXE menu for Standard PCs

Adds a machine number prompt to startnet.cmd after the Standard sub-type
selection. Tech enters the number during the PXE boot process. Defaults
to 9999 if Enter is pressed (existing placeholder behavior).

Written to C:\Enrollment\machine-number.txt alongside pc-type.txt.

Consumers:
  00-PreInstall-MachineApps.ps1 - replaces 9999 in UDC InstallArgs with
    the entered number, so UDC installs with the correct machine number
    from the start (no post-setup Set-MachineNumber needed).
  01-eDNC.ps1 - writes the machine number to the DNC\General\MachineNo
    registry value during eDNC install.
  Configure-PC.ps1 - existing $needsMachineNumber check already skips
    the prompt when UDC/eDNC aren't at 9999, so no change needed.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

playbook/shopfloor-setup/Shopfloor/00-PreInstall-MachineApps.ps1

@@ -129,6 +129,25 @@ if ($siteConfig -and $siteConfig.siteName -and $siteConfig.siteName -ne 'West Je
     Write-PreInstallLog "No site-config override for siteName (using defaults in preinstall.json)"
 }
 
+# --- Machine-number override: replace "9999" in UDC InstallArgs if tech entered a number ---
+$machineNumFile = 'C:\Enrollment\machine-number.txt'
+if (Test-Path -LiteralPath $machineNumFile) {
+    $machineNum = (Get-Content -LiteralPath $machineNumFile -First 1 -ErrorAction SilentlyContinue).Trim()
+    if ($machineNum -and $machineNum -ne '9999' -and $machineNum -match '^\d+$') {
+        Write-PreInstallLog "Machine number from PXE menu: $machineNum"
+        foreach ($app in $config.Applications) {
+            if ($app.InstallArgs -and $app.InstallArgs -match '9999') {
+                $app.InstallArgs = $app.InstallArgs -replace '9999', $machineNum
+                Write-PreInstallLog "  Overrode machine number in $($app.Name) args: $($app.InstallArgs)"
+            }
+        }
+    } else {
+        Write-PreInstallLog "Machine number: $machineNum (default placeholder)"
+    }
+} else {
+    Write-PreInstallLog "No machine-number.txt found (using 9999 default)"
+}
+
 # --- Detection helper (mirrors Simple-Install.ps1's Test-ApplicationInstalled) ---
 function Test-AppInstalled {
     param($App)