fix(install): migrate duplicate skills and resolve concurrency tokens

scripts/lib/manifest.ps1

@@ -70,6 +70,7 @@ function Sync-ManagedDestination {
 
     Get-ChildItem $Source -File -Recurse | ForEach-Object {
         $relative = $_.FullName.Substring($Source.Length).TrimStart([char[]]@('\','/')).Replace('\','/')
+        if ((Split-Path $Destination -Leaf) -eq '.codex' -and $relative.StartsWith('skills/')) { return }
         $target = Join-Path $Destination $relative
         $rawContent = Get-Content -LiteralPath $_.FullName -Raw -Encoding UTF8
         $filterFlashbang = -not $FlashbangEnabled -and $relative -in @('settings.json', 'config.toml')
@@ -77,7 +78,7 @@ function Sync-ManagedDestination {
             $rawContent = (& python (Join-Path $PSScriptRoot 'install-options.py') filter --path $_.FullName --flashbang false | Out-String)
             if ($LASTEXITCODE -ne 0) { throw 'Could not configure Flashbang.' }
         }
-        $needsSubstitution = $filterFlashbang -or $rawContent.Contains('__AI_CONFIG_ROOT__') -or $rawContent.Contains('__HOOK_COMMAND__') -or $rawContent.Contains('__POWERSHELL_HOOK_COMMAND__') -or $rawContent.Contains('__POWERSHELL_COMMAND__')
+        $needsSubstitution = $filterFlashbang -or $rawContent.Contains('__AI_CONFIG_ROOT__') -or $rawContent.Contains('__HOOK_COMMAND__') -or $rawContent.Contains('__POWERSHELL_HOOK_COMMAND__') -or $rawContent.Contains('__POWERSHELL_COMMAND__') -or $rawContent.Contains('__CLAUDE_CODE_MAX_TOOL_USE_CONCURRENCY__')
         if ($needsSubstitution) {
             $finalContent = $rawContent.Replace('__AI_CONFIG_ROOT__', $AiConfigRoot).Replace('__HOOK_COMMAND__', $ShellCommand).Replace('__POWERSHELL_HOOK_COMMAND__', $PowerShellCommand).Replace('__POWERSHELL_COMMAND__', $PowerShellCommand).Replace('__CLAUDE_CODE_MAX_TOOL_USE_CONCURRENCY__', $ClaudeConcurrency).Replace('__HOOK_SCRIPT__', 'flashbang.ps1').Replace('__POWERSHELL_HOOK_SCRIPT__', 'flashbang.ps1')
             $newBytes = [System.Text.Encoding]::UTF8.GetBytes($finalContent)