Critical bug fix for Windows PowerShell script installers:
- Use shutil.which() to find full path to powershell.exe
- Fall back to common Windows locations if not in PATH
- Fixes FileNotFoundError for 6 tools: phpstan, ktlint, checkstyle, taplo, clj-kondo

This resolves the [WinError 2] issue blocking automated installation
of tools that require custom PowerShell scripts on Windows.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>