Stop Display bays getting machine-tool shortcuts, prompts and the S: mapper

Three fixes from the 579C144 diagnostics, all the same shape: a Display kiosk
being treated as a machine-tool bay.

desktopApps: configuring "none" produced "everything"

  "Display-Dashboard": { "desktopApps": [] }

06-OrganizeDesktop.ps1 tested $null -ne $cfgApps -AND .Count -gt 0, so an
explicitly empty list fell through to the hardcoded fallback and the kiosk was
given UDC, eDNC, NTLARS, WJ Shopfloor and Defect_Tracker shortcuts.
Get-ProfileValue returns $null only when the key is ABSENT from both the profile
and site-config, so $null is the real "not configured" signal and an empty array
means what it says. startupItems carried the same test - harmless today because
its else branch has no fallback list, but commented so the two cannot drift.

Machine-number prompt on a machine with no machine number

Register-CheckMachineNumberTask.ps1 armed 'Prompt Machine Number' (AtLogOn,
BUILTIN\Users) whenever the number was the 9999 placeholder - which is always
true on a Display, because startnet only collects a real number for machine-tool
types. A logon dialog on a kiosk with no keyboard. Now skips PC types that have
no machine number by design, and clears any stale task.

S: mapper on a share-less PC

Displays are Entra-joined with local accounts and no SFLD credentials, so mapping
S: can only fail, once per logon, forever. Run-ShopfloorSetup already gated the
CALL on $noEnforceTypes, but the bay registered it anyway at 15:07:55 with no
"Skipping" line in the log - so something in the finalization phase reaches the
registrar past that gate. Rather than chase the caller, the registrar now gates
itself and removes a stale Run entry. The call-site gate stays; this makes the
outcome correct regardless of who invokes it.

That bypass is worth understanding separately - the same pattern would defeat any
call-site gate in the finalization phase.

All three parse clean and are deployed byte-identical to the share.

playbook/shopfloor-setup/Shopfloor/Register-CheckMachineNumberTask.ps1

@@ -50,6 +50,36 @@ try {
     }
 } catch { Write-RegLog "Could not unregister legacy '$oldTaskName': $_" }
 
+# PC types that have no machine number by design. Arming the prompt on these
+# guarantees a dialog nobody can answer: startnet only collects a machine number
+# for the machine-tool types, so everything else is left on the 9999 placeholder
+# and the check below would otherwise fire on every one of them.
+#
+# Observed on 579C144 (a Display) 2026-08-06: PreInstall logged
+# "Machine number: 9999 (default placeholder)" and the logon prompt armed itself
+# on a kiosk with no keyboard.
+$noMachineNumberTypes = @(
+    'gea-shopfloor-display'
+)
+$pcTypeFile = 'C:\Enrollment\pc-type.txt'
+$pcType = ''
+if (Test-Path -LiteralPath $pcTypeFile) {
+    $pcType = (Get-Content -LiteralPath $pcTypeFile -First 1 -ErrorAction SilentlyContinue)
+    if ($pcType) { $pcType = $pcType.Trim() }
+}
+if ($pcType -and ($noMachineNumberTypes -contains $pcType)) {
+    Write-RegLog "PC type '$pcType' has no machine number by design. Not registering the prompt."
+    foreach ($t in @($promptTaskName, $applyTaskName)) {
+        try {
+            if (Get-ScheduledTask -TaskName $t -ErrorAction SilentlyContinue) {
+                Unregister-ScheduledTask -TaskName $t -Confirm:$false -ErrorAction Stop
+                Write-RegLog "Unregistered stale task '$t'"
+            }
+        } catch {}
+    }
+    return
+}
+
 # Only arm the tasks if the bay was imaged with the 9999 placeholder. If
 # the tech entered a real machine number during PXE imaging it's already
 # in C:\Enrollment\machine-number.txt; no prompt needed on first logon.