Add Windows PowerShell dev workflow

scripts/setup-dev.ps1

@@ -0,0 +1,43 @@
+param(
+    [switch]$SkipPythonDeps,
+    [switch]$SkipGoDownload,
+    [switch]$SkipFFmpegDownload,
+    [switch]$UpgradePip
+)
+
+Set-StrictMode -Version Latest
+$ErrorActionPreference = "Stop"
+
+. (Join-Path $PSScriptRoot "dev-tools.ps1")
+
+Use-LocalTooling
+Ensure-Directory -Path (Get-ToolsRoot)
+Ensure-Directory -Path (Get-LocalRoot)
+
+$pythonExe = Ensure-Venv
+Write-Step "Python 사용 경로: $pythonExe"
+
+if (-not $SkipPythonDeps) {
+    Install-PythonRequirements -UpgradePip:$UpgradePip
+}
+
+Ensure-CommandShims
+
+if (-not $SkipGoDownload -and -not (Test-GoReady)) {
+    Install-LocalGo
+}
+
+if (-not $SkipFFmpegDownload -and -not (Test-FFmpegReady)) {
+    Install-LocalFFmpeg
+}
+
+Use-LocalTooling
+
+Write-Step "준비 상태"
+Write-Host ("  python3: " + ((Resolve-SystemCommand -Name "python3") ?? "미설치"))
+Write-Host ("  python : " + ((Resolve-SystemCommand -Name "python") ?? "미설치"))
+Write-Host ("  yt-dlp : " + ((Resolve-SystemCommand -Name "yt-dlp") ?? "미설치"))
+Write-Host ("  go     : " + ((Resolve-SystemCommand -Name "go") ?? "미설치"))
+Write-Host ("  ffmpeg : " + ((Resolve-SystemCommand -Name "ffmpeg") ?? "미설치"))
+Write-Step "현재 셸에 PATH를 적용하려면 다음처럼 dot-source 하세요."
+Write-Host "  . .\scripts\enter-dev-shell.ps1"