fix: use native scheduled task cmdlets and improve error diagnostics

scripts/uninstall.ps1

@@ -1,10 +1,9 @@
 param([string]$InstallDirectory = "$env:ProgramFiles\NetBox Windows Agent")
 $ErrorActionPreference = 'Stop'
-schtasks.exe /Delete /TN 'NetBox Windows Agent' /F 2>$null
+Unregister-ScheduledTask -TaskName 'NetBox Windows Agent' -Confirm:$false -ErrorAction SilentlyContinue
 if (Test-Path -LiteralPath $InstallDirectory) {
     $resolved = (Resolve-Path -LiteralPath $InstallDirectory).Path
     $programFiles = (Resolve-Path -LiteralPath $env:ProgramFiles).Path
     if (-not $resolved.StartsWith($programFiles + '\', [StringComparison]::OrdinalIgnoreCase)) { throw "Unsicheres Ziel: $resolved" }
     Remove-Item -LiteralPath $resolved -Recurse -Force
 }
-