Prepare 0.3.0-rc.2 with Windows support and regression tests

scripts/windows_common.ps1

@@ -0,0 +1,62 @@
+Set-StrictMode -Version Latest
+$ErrorActionPreference = "Stop"
+
+$script:RepoRoot = Split-Path -Parent $PSScriptRoot
+
+function Require-Tool {
+    param(
+        [Parameter(Mandatory = $true)]
+        [string]$Name,
+        [Parameter(Mandatory = $true)]
+        [string]$Hint
+    )
+
+    if (Get-Command $Name -ErrorAction SilentlyContinue) {
+        return
+    }
+
+    throw "Required tool '$Name' was not found on PATH. $Hint"
+}
+
+function Warn-If-Missing {
+    param(
+        [Parameter(Mandatory = $true)]
+        [string]$Name,
+        [Parameter(Mandatory = $true)]
+        [string]$Hint
+    )
+
+    if (Get-Command $Name -ErrorAction SilentlyContinue) {
+        return
+    }
+
+    Write-Warning "Optional tool '$Name' was not found on PATH. $Hint"
+}
+
+function Invoke-Native {
+    param(
+        [Parameter(Mandatory = $true)]
+        [string[]]$Command,
+        [string]$WorkingDirectory = $script:RepoRoot,
+        [string]$Label = ""
+    )
+
+    if ($Label) {
+        Write-Host "── $Label ──"
+    }
+
+    Push-Location $WorkingDirectory
+    try {
+        if ($Command.Count -gt 1) {
+            & $Command[0] @($Command[1..($Command.Count - 1)])
+        } else {
+            & $Command[0]
+        }
+
+        if ($LASTEXITCODE -ne 0) {
+            throw "Command failed ($LASTEXITCODE): $($Command -join ' ')"
+        }
+    } finally {
+        Pop-Location
+    }
+}