fix: use Register-ScheduledTask -Force instead of delete-then-create to avoid losing tasks on failure

scripts/install.ps1

@@ -563,9 +563,6 @@ function Setup-AutoStart {
 "@
     $hubScript | Set-Content $hubScriptPath -Encoding UTF8
 
-    $oldHub = Get-ScheduledTask -TaskName "HAPI Hub" -ErrorAction SilentlyContinue
-    if ($oldHub) { Unregister-ScheduledTask -TaskName "HAPI Hub" -Confirm:$false }
-
     $trigger = New-ScheduledTaskTrigger -AtLogon
     $action = New-ScheduledTaskAction -Execute "powershell.exe" `
         -Argument "-WindowStyle Hidden -ExecutionPolicy Bypass -File `"$hubScriptPath`""
@@ -577,9 +574,6 @@ function Setup-AutoStart {
         -Principal $principal -Settings $settings -Force | Out-Null
     Write-Ok "HAPI Hub 计划任务已创建"
 
-    $oldRunner = Get-ScheduledTask -TaskName "HAPI Runner" -ErrorAction SilentlyContinue
-    if ($oldRunner) { Unregister-ScheduledTask -TaskName "HAPI Runner" -Confirm:$false }
-
     $hapiHome = Join-Path $env:USERPROFILE ".hapi"
     New-Item -ItemType Directory -Force -Path $hapiHome | Out-Null
     $settingsJson = @"