fix(plugins): correct navigation keys and menu encoding

scripts/lib/plugins.ps1

@@ -88,7 +88,7 @@ function Read-PluginToggleSelection {
     )
     $state = @($Checked)
     if ([Console]::IsInputRedirected -or $env:CI -eq 'true' -or $env:AI_CONFIG_NO_INTERACTIVE -eq '1') { while($true){ Write-Host 'Select plugins (enter a number to toggle, "done" to confirm):'; for($i=0;$i -lt $Names.Count;$i++){Write-Host ("  {0}) [{1}] {2}" -f ($i+1),$(if($state[$i]){'x'}else{' '}),$Names[$i])}; $answer=Read-Host 'Toggle number or "done"'; if([string]::IsNullOrWhiteSpace($answer)-or $answer -eq 'done'){return $state}; $index=0;if([int]::TryParse($answer,[ref]$index)-and $index -ge 1 -and $index -le $Names.Count){$state[$index-1]= -not $state[$index-1]} } }
-    $index=0; while($true){ Clear-Host; Write-Host 'Select plugins'; for($i=0;$i -lt $Names.Count;$i++){ $focus=if($i -eq $index){'>'}else{' '}; $mark=if($state[$i]){'x'}else{' '}; Write-Host "$focus [$mark] $($Names[$i])" }; Write-Host '↑/↓ Navigate   Space Toggle   Enter Confirm'; $key=[Console]::ReadKey($true); if($key.Key -eq 'Up'){$index=($index+$Names.Count-1)%$Names.Count}elseif($key.Key -eq 'Down'){$index=($index+1)%$Names.Count}elseif($key.Key -eq 'Spacebar'){$state[$index]= -not $state[$index]}elseif($key.Key -eq 'Enter'){Clear-Host;return $state} }
+    $index=0; while($true){ Clear-Host; Write-Host 'Select plugins'; for($i=0;$i -lt $Names.Count;$i++){ $focus=if($i -eq $index){'>'}else{' '}; $mark=if($state[$i]){'x'}else{' '}; Write-Host "$focus [$mark] $($Names[$i])" }; Write-Host 'Up/Down Navigate   Space Toggle   Enter Confirm'; $key=[Console]::ReadKey($true); if($key.Key -eq 'UpArrow'){$index=($index+$Names.Count-1)%$Names.Count}elseif($key.Key -eq 'DownArrow'){$index=($index+1)%$Names.Count}elseif($key.Key -eq 'Spacebar'){$state[$index]= -not $state[$index]}elseif($key.Key -eq 'Enter'){Clear-Host;return $state} }
 }
 
 function Update-CodexMarketplace {