feat: Windows/PowerShell port and CLAUDE.md

[dtsong]

Context

This repo is macOS/bash-only with no Windows equivalent. Our consultancy team works primarily on Windows.

Requested Changes

1. Windows/PowerShell Port

• Port setup scripts to PowerShell equivalents
• OR provide WSL setup instructions for Windows users
• Document any macOS-specific assumptions

2. Missing CLAUDE.md

• Add project conventions file
• Include setup commands, contribution guidelines, and project structure

3. Staleness

• Last updated Feb 13, 2026
• Needs sync with latest patterns from my-claude-setup

Priority

Medium — blocked on deciding between native PowerShell port vs WSL-only support.