Added PowerShell installers for:
- ktlint (Kotlin linter - JAR)
- checkstyle (Java checker - JAR)
- phpstan (PHP analyzer - PHAR)

All installers follow lessons learned from clj-kondo:
- No emojis (prevent Windows parsing errors)
- UTF-8 encoding
- GitHub API for latest releases
- Install to %LOCALAPPDATA%
- Create .bat wrapper scripts
- Verify runtime dependencies (Java/PHP)

This brings total PowerShell installers to 4 tools.

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

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