HeatTreat: bump DNC app 6.2.1 -> 6.4.9

Replace HeatTreat_6.2.1.msi with HeatTreat_6-4-9.msi (ProductVersion
6.4.9.0, ProductCode {9E603EFE-888A-4E3F-8CF5-7F03B7029919}). The install
script globs HeatTreat*.msi so no logic change; the MSI's NOT
NEWERVERSIONDETECTED LaunchCondition makes 6.2.1 -> 6.4.9 a clean
in-place upgrade. Update version references in 02-Setup-HeatTreat.ps1.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

playbook/shopfloor-setup/gea-shopfloor-heattreat/02-Setup-HeatTreat.ps1

@@ -1,6 +1,6 @@
 # 02-Setup-HeatTreat.ps1 - HeatTreat app setup (runs AFTER 01-eDNC.ps1).
 #
-# HeatTreat_6.2.1.msi is a WiX/GE Aviation installer, same lineage as Mark
+# HeatTreat_6-4-9.msi is a WiX/GE Aviation installer, same lineage as Mark
 # and eDNC. Decompiled findings:
 #   - LAUNCHNTLARS=true by default and the LaunchNtlars custom action fires
 #     under /qn (condition NOT Installed AND LAUNCHNTLARS="true"). Pass
@@ -34,7 +34,7 @@ if (Test-Path $pxeStatusLib) {
 $payloadDir = Join-Path $PSScriptRoot 'HeatTreat'
 
 # ============================================================================
-# Install HeatTreat_6.2.1.msi
+# Install HeatTreat_6-4-9.msi
 # ============================================================================
 $htMsi = Get-ChildItem -Path $payloadDir -Filter 'HeatTreat*.msi' -File -ErrorAction SilentlyContinue | Select-Object -First 1
 if ($htMsi) {