fix: use native scheduled task cmdlets and improve error diagnostics

scripts/install.ps1

@@ -17,6 +17,12 @@ $systemSid = New-Object System.Security.Principal.SecurityIdentifier('S-1-5-18')
 $admins = New-Object System.Security.AccessControl.FileSystemAccessRule($administratorsSid, 'FullControl', 'ContainerInherit,ObjectInherit', 'None', 'Allow')
 $system = New-Object System.Security.AccessControl.FileSystemAccessRule($systemSid, 'FullControl', 'ContainerInherit,ObjectInherit', 'None', 'Allow')
 $acl.SetAccessRule($admins); $acl.SetAccessRule($system); Set-Acl $InstallDirectory $acl
-$command = '"' + (Join-Path $InstallDirectory 'agent.exe') + '" --config "' + (Join-Path $InstallDirectory 'config.json') + '"'
-schtasks.exe /Create /TN 'NetBox Windows Agent' /SC $Schedule /ST $StartTime /RU SYSTEM /RL HIGHEST /TR $command /F | Out-Null
+$agentPath = Join-Path $InstallDirectory 'agent.exe'
+$configPath = Join-Path $InstallDirectory 'config.json'
+if ($Schedule -ne 'DAILY') { throw "Derzeit wird nur Schedule 'DAILY' unterstützt." }
+$action = New-ScheduledTaskAction -Execute $agentPath -Argument "--config `"$configPath`""
+$trigger = New-ScheduledTaskTrigger -Daily -At $StartTime
+$principal = New-ScheduledTaskPrincipal -UserId 'S-1-5-18' -LogonType ServiceAccount -RunLevel Highest
+$settings = New-ScheduledTaskSettingsSet -StartWhenAvailable -ExecutionTimeLimit (New-TimeSpan -Minutes 15)
+Register-ScheduledTask -TaskName 'NetBox Windows Agent' -Action $action -Trigger $trigger -Principal $principal -Settings $settings -Force | Out-Null
 & (Join-Path $InstallDirectory 'agent.exe') --config (Join-Path $InstallDirectory 'config.json')

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
 }
-

src/Program.cs

@@ -21,7 +21,14 @@ static async Task<int> MainAsync(string[] args)
         Console.WriteLine(dryRun ? "Dry-Run erfolgreich; keine Änderungen geschrieben." : $"Synchronisiert: Device #{result.DeviceId}, Asset #{result.AssetId}");
         return 0;
     }
-    catch (Exception ex) { Console.Error.WriteLine($"FEHLER: {ex.Message}"); return 1; }
+    catch (Exception ex)
+    {
+        var messages = new List<string>();
+        for (Exception? current = ex; current is not null; current = current.InnerException)
+            if (!messages.Contains(current.Message)) messages.Add(current.Message);
+        Console.Error.WriteLine($"FEHLER: {string.Join(" -> ", messages)}");
+        return 1;
+    }
 }
 static string? ValueAfter(string[] args, string key) { var i = Array.IndexOf(args, key); return i >= 0 && i + 1 < args.Length ? args[i + 1] : null; }
 static void Validate(AgentConfig c)