Add Windows direct install script

[efrazer-oai]

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 Add macOS and Linux direct install script #12740

Testing

• Smoke-tested with powershell

[github-actions]

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