feat(credentials): add scoped credential helpers

scripts/commands/add-credentials.ps1

@@ -0,0 +1,39 @@
+[CmdletBinding()]
+param(
+    [ValidateSet('Codex', 'Claude', 'Both')][string]$Client,
+    [string]$Key,
+    [switch]$ValueFromStdin,
+    [string]$HomePath = [Environment]::GetFolderPath('UserProfile')
+)
+$ErrorActionPreference = 'Stop'
+$root = Split-Path (Split-Path $PSScriptRoot -Parent) -Parent
+. (Join-Path $root 'scripts/lib/install-targets.ps1')
+$selectedClient = $Client
+$selectedKey = $Key
+. (Join-Path $root 'scripts/lib/credentials.ps1')
+$Client = $selectedClient
+$Key = $selectedKey
+
+if (-not $Client) { $Client = Read-InstallClient -Client $Client }
+if (-not $Key) { $Key = Read-Host 'Credential key' }
+Assert-CredentialKey $Key
+if (-not [System.IO.Path]::IsPathRooted($HomePath)) { throw 'HomePath must be absolute.' }
+if ($ValueFromStdin) {
+    $text = [Console]::In.ReadToEnd().TrimEnd("`r", "`n")
+    $Value = ConvertTo-SecureString $text -AsPlainText -Force
+    $text = $null
+} else {
+    $Value = Read-Host 'Credential value' -AsSecureString
+}
+
+$bin = Join-Path $HomePath '.my-ai-configuration/bin'
+New-Item -ItemType Directory -Path $bin -Force | Out-Null
+foreach ($source in @('credentials.ps1', 'with-credential.sh')) {
+    $destination = Join-Path $bin $(if ($source -eq 'credentials.ps1') { 'with-credential.ps1' } else { $source })
+    if (-not (Test-Path -LiteralPath $destination)) { Copy-Item (Join-Path $root "scripts/lib/$source") $destination }
+}
+foreach ($target in $(if ($Client -eq 'Both') { @('Codex', 'Claude') } else { @($Client) })) {
+    Set-ManagedCredential $target $Key $Value
+    Write-Output "Credential stored for $($target.ToLowerInvariant())."
+}
+$Value = $null

scripts/commands/add-credentials.sh

@@ -0,0 +1,28 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+client=
+key=
+home_path=${HOME:?HOME is required}
+while [ $# -gt 0 ]; do
+  case "$1" in
+    --client) client=${2:?--client requires a value}; shift 2 ;;
+    --key) key=${2:?--key requires a value}; shift 2 ;;
+    --home) home_path=${2:?--home requires a value}; shift 2 ;;
+    *) printf 'Unknown argument: %s\n' "$1" >&2; exit 1 ;;
+  esac
+done
+
+[ -n "$client" ] || read -r -p 'Select client (codex, claude, or both) ' client
+[ -n "$key" ] || read -r -p 'Credential key ' key
+case "$client" in codex|Codex|claude|Claude|both|Both) ;; *) printf 'Unknown --client value: %s\n' "$client" >&2; exit 1 ;; esac
+case "$key" in [A-Za-z_][A-Za-z0-9_]* ) ;; *) printf 'Credential key must be an environment-variable-compatible name.\n' >&2; exit 1 ;; esac
+case "$home_path" in /*|[A-Za-z]:[\\/]*) ;; *) printf 'Home path must be absolute.\n' >&2; exit 1 ;; esac
+
+IFS= read -r -s -p 'Credential value ' value
+printf '\n'
+powershell_command=$(command -v powershell.exe || command -v powershell || command -v pwsh || true)
+[ -n "$powershell_command" ] || { printf 'PowerShell is required to store credentials in the Windows credential store.\n' >&2; exit 1; }
+script_dir=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)
+printf '%s' "$value" | "$powershell_command" -NoProfile -ExecutionPolicy Bypass -File "$script_dir/add-credentials.ps1" -Client "$client" -Key "$key" -ValueFromStdin -HomePath "$home_path"
+unset value