Add Windows direct install script (#12741)

## Summary
- add a direct install script for Windows at
`scripts/install/install.ps1`
- extend release staging so `install.ps1` is published alongside
`install.sh`
- install the Windows runtime payload (`codex.exe`, `rg.exe`, and helper
binaries) from the existing platform npm package

## Dependencies
- Depends on https://github.com/openai/codex/pull/12740

## Testing
- Smoke-tested with powershell

.github/workflows/rust-release.yml

@@ -494,9 +494,10 @@ jobs:
             --package codex-responses-api-proxy \
             --package codex-sdk
 
-      - name: Stage macOS and Linux installer script
+      - name: Stage installer scripts
         run: |
           cp scripts/install/install.sh dist/install.sh
+          cp scripts/install/install.ps1 dist/install.ps1
 
       - name: Create GitHub Release
         uses: softprops/action-gh-release@v2