Fix stage gate infinite loop: -FromDispatcher bypass

The stage-file gate in Run-ShopfloorSetup.ps1 would fire even when
called by Stage-Dispatcher.ps1 (because the stage file still contains
"shopfloor-setup"), causing an infinite exit loop.

Fix: Run-ShopfloorSetup now accepts -FromDispatcher switch. The gate
only fires when the switch is absent (i.e. when called by the unattend's
FirstLogonCommands). Stage-Dispatcher passes -FromDispatcher when
invoking Run-ShopfloorSetup, bypassing the gate.

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

playbook/shopfloor-setup/Run-ShopfloorSetup.ps1

@@ -1,6 +1,13 @@
 # Run-ShopfloorSetup.ps1 - Dispatcher for shopfloor PC type setup
 # Runs Shopfloor baseline scripts first, then type-specific scripts on top.
 
+param(
+    # Stage-Dispatcher.ps1 passes -FromDispatcher to bypass the stage-file
+    # gate below. When called by the unattend's FirstLogonCommands (no flag),
+    # the gate defers to the dispatcher if a stage file exists.
+    [switch]$FromDispatcher
+)
+
 # --- Stage-file gate ---
 # If run-enrollment.ps1 wrote a stage file, the imaging chain is managed by
 # Stage-Dispatcher.ps1 via RunOnce. Exit immediately so the FirstLogonCommands
@@ -8,11 +15,13 @@
 # the next boot. Without this gate, the unattend's FirstLogonCommands runs
 # this script right after run-enrollment in the same session (before the
 # PPKG reboot), bypassing the entire staged chain.
-$stageFile = 'C:\Enrollment\setup-stage.txt'
-if (Test-Path -LiteralPath $stageFile) {
-    $stage = (Get-Content -LiteralPath $stageFile -First 1 -ErrorAction SilentlyContinue)
-    Write-Host "Stage file found ($stage) - deferring to Stage-Dispatcher.ps1 on next logon."
-    exit 0
+if (-not $FromDispatcher) {
+    $stageFile = 'C:\Enrollment\setup-stage.txt'
+    if (Test-Path -LiteralPath $stageFile) {
+        $stage = (Get-Content -LiteralPath $stageFile -First 1 -ErrorAction SilentlyContinue)
+        Write-Host "Stage file found ($stage) - deferring to Stage-Dispatcher.ps1 on next logon."
+        exit 0
+    }
 }
 
 # --- Transcript logging ---