demo: add Windows PowerShell twin (portability-demo.ps1) + README note

Same offline audit + both compiles as the .sh, native to PowerShell so Windows
users don't need bash. README points to it next to the .sh.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: phuryn

README.md

@@ -180,7 +180,7 @@ $ agentlift audit ./examples/team --targets anthropic,google,openai
 
 The audit's `degraded`/`unsupported` rows are exactly the lossy spots a compile would hit — so `audit` tells you what survives before `export` or `deploy` runs.
 
-See the whole thing run offline (audit + both compiles, no API key) in [`demo/`](demo/): `./demo/portability-demo.sh`.
+See the whole thing run offline (audit + both compiles, no API key) in [`demo/`](demo/): `./demo/portability-demo.sh` (Windows: `.\demo\portability-demo.ps1`).
 
 A subagent roster is a **universal** capability, not a per-provider lottery: `native` on Anthropic (server-side coordinator), `emulated` elsewhere via agent-as-tool. Confirmed by actually running it on OpenAI (Agents SDK `as_tool`) and Google (ADK `sub_agents`) in [`experiments/subagent-composition`](experiments/subagent-composition/) — the only difference is whether the delegation loop runs in the provider's runtime or yours. Full per-platform test receipts, including a **live Google Agent Engine deploy** (a real `reasoningEngine`, server-side delegation confirmed) and the console/docs links for each provider: [`docs/tested-platforms.md`](docs/tested-platforms.md).
 

demo/portability-demo.ps1

@@ -0,0 +1,32 @@
+# agentlift portability demo (Windows / PowerShell) - a twin of portability-demo.sh.
+# Everything here is OFFLINE: no API key, nothing deployed. It shows the compiler,
+# not a live deploy.
+#
+#   pip install agentlift   # or: pip install -e .  (from a clone)
+#   .\demo\portability-demo.ps1
+#
+$ErrorActionPreference = "Stop"
+$Root  = Split-Path -Parent $PSScriptRoot            # repo root (parent of demo/)
+$Agent = Join-Path $Root "examples\team"
+$Out   = if ($args.Count -ge 1) { $args[0] } else { Join-Path $Root "demo\out" }
+
+# Use the installed CLI if present, else the module form from a checkout.
+if (Get-Command agentlift -ErrorAction SilentlyContinue) {
+    $AlExe = "agentlift"; $AlArgs = @()
+} else {
+    $AlExe = "python"; $AlArgs = @("-m", "agentlift.cli")
+}
+
+if (Test-Path $Out) { Remove-Item -Recurse -Force $Out }
+
+Write-Host "### 1. AUDIT - how portable is examples/team across providers?"
+& $AlExe @AlArgs audit $Agent --targets anthropic,google,openai
+
+Write-Host "`n### 2. EXPORT -> Anthropic YAML (the shape the official 'ant' CLI consumes)"
+& $AlExe @AlArgs export anthropic-yaml $Agent --out (Join-Path $Out "anthropic")
+
+Write-Host "`n### 3. EXPORT -> Google ADK (Vertex AI Agent Engine scaffold, preview)"
+& $AlExe @AlArgs export google-adk $Agent --out (Join-Path $Out "google")
+
+Write-Host "`nDone. One folder -> audited across 3 providers and compiled to 2 formats."
+Write-Host "Artifacts: $Out"