fix(windows-msi): inject rev into MSI Version Build field

Version was static (X.Y.Z.0) across nightlies, so MajorUpgrade never triggered the automatic uninstall; the Windows Installer only compares Major.Minor.Build, ignoring the 4th field.

.github/workflows/windows-msi.yml

@@ -74,9 +74,6 @@ jobs:
             }
           }
 
-          # Numeric MSI version: 4 digits required (e.g. 0.100.1.0)
-          $verMsi = "$ver.0"
-
           # Short SHA for the display version
           $sha = git rev-parse --short HEAD 2>$null
           if (-not $sha) { $sha = "unknown" }
@@ -85,6 +82,13 @@ jobs:
           $count = git rev-list HEAD --count 2>$null
           $rev = [int]$count + 473
 
+          # MSI Version only compares Major.Minor.Build (the 4th field is
+          # ignored by Windows Installer for upgrade detection), so we
+          # inject rev into Build to force a real increase between
+          # nightlies and trigger MajorUpgrade's automatic uninstall.
+          $verParts = $ver -split '\.'
+          $verMsi = "$($verParts[0]).$($verParts[1]).$($rev % 65535)"
+
           $verDisplay = "${ver}-r${rev}-${sha}_x86_64-win64"
 
           echo "VERSION_MSI=$verMsi"       >> $env:GITHUB_OUTPUT