Refactor with platform-specific constraints

scripts/powershell/setup-plan.ps1

@@ -0,0 +1,21 @@
+#!/usr/bin/env pwsh
+[CmdletBinding()]
+param([switch]$Json)
+$ErrorActionPreference = 'Stop'
+. "$PSScriptRoot/common.ps1"
+
+$paths = Get-FeaturePathsEnv
+if (-not (Test-FeatureBranch -Branch $paths.CURRENT_BRANCH)) { exit 1 }
+
+New-Item -ItemType Directory -Path $paths.FEATURE_DIR -Force | Out-Null
+$template = Join-Path $paths.REPO_ROOT 'templates/plan-template.md'
+if (Test-Path $template) { Copy-Item $template $paths.IMPL_PLAN -Force }
+
+if ($Json) {
+    [PSCustomObject]@{ FEATURE_SPEC=$paths.FEATURE_SPEC; IMPL_PLAN=$paths.IMPL_PLAN; SPECS_DIR=$paths.FEATURE_DIR; BRANCH=$paths.CURRENT_BRANCH } | ConvertTo-Json -Compress
+} else {
+    Write-Output "FEATURE_SPEC: $($paths.FEATURE_SPEC)"
+    Write-Output "IMPL_PLAN: $($paths.IMPL_PLAN)"
+    Write-Output "SPECS_DIR: $($paths.FEATURE_DIR)"
+    Write-Output "BRANCH: $($paths.CURRENT_BRANCH)"
+}