fix: build-update.ps1 obsługa SQL-only paczek (0 plików)

Skrypt failował przy Set-Location do temp dir który nie istniał
gdy paczka nie miała plików (tylko migracja SQL).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

build-update.ps1

@@ -262,6 +262,10 @@ if (Test-Path $tempDir) {
     Remove-Item -Recurse -Force $tempDir
 }
 
+if (-not (Test-Path $tempDir)) {
+    New-Item -ItemType Directory -Path $tempDir -Force | Out-Null
+}
+
 foreach ($f in $filesToPack) {
     $destPath = Join-Path $tempDir $f
     $destDir = Split-Path $destPath -Parent
@@ -295,7 +299,16 @@ if (Test-Path $zipPath) {
 # Pakuj zawartosc temp dir (bez folderu temp/)
 $originalLocation = Get-Location
 Set-Location $tempDir
-Compress-Archive -Path '*' -DestinationPath "../../$zipPath" -Force
+$tempItems = Get-ChildItem -Force
+if ($tempItems) {
+    Compress-Archive -Path '*' -DestinationPath "../../$zipPath" -Force
+} else {
+    # SQL-only update: create minimal ZIP with empty placeholder
+    $placeholderPath = "_sql_only_update.txt"
+    Set-Content -Path $placeholderPath -Value "SQL-only update $versionNumber"
+    Compress-Archive -Path $placeholderPath -DestinationPath "../../$zipPath" -Force
+    Remove-Item $placeholderPath -Force
+}
 Set-Location $originalLocation
 
 Write-Ok "Utworzono ZIP: $zipPath"